Update environment variable terminology

Make sure environment variables are referred to as
CI/CD variables or environment variables, as needed

doc/administration/troubleshooting/elasticsearch.md

@@ -294,7 +294,7 @@ Beyond that, you will want to review the error. If it is:
   GitLab support.
 - An OS issue, you will want to reach out to your systems administrator.
 - A `Faraday::TimeoutError (execution expired)` error **and** you're using a proxy,
-  [set a custom  `gitlab_rails['env']` environment variable, called `no_proxy`](https://docs.gitlab.com/omnibus/settings/environment-variables.html)
+  [set a custom `gitlab_rails['env']` environment variable, called `no_proxy`](https://docs.gitlab.com/omnibus/settings/environment-variables.html)
   with the IP address of your Elasticsearch host.
 
 ### Troubleshooting performance

doc/api/settings.md

@@ -335,7 +335,7 @@ listed in the descriptions of the relevant settings.
 | `polling_interval_multiplier`            | decimal          | no                                   | Interval multiplier used by endpoints that perform polling. Set to `0` to disable polling. |
 | `project_export_enabled`                 | boolean          | no                                   | Enable project export. |
 | `prometheus_metrics_enabled`             | boolean          | no                                   | Enable Prometheus metrics. |
-| `protected_ci_variables`                 | boolean          | no                                   | Environment variables are protected by default. |
+| `protected_ci_variables`                 | boolean          | no                                   | CI/CD variables are protected by default. |
 | `pseudonymizer_enabled`                  | boolean          | no                                   | **(PREMIUM)** When enabled, GitLab runs a background job that produces pseudonymized CSVs of the GitLab database to upload to your configured object storage directory.
 | `push_event_activities_limit`            | integer          | no                                   | Number of changes (branches or tags) in a single push to determine whether individual push events or bulk push events are created. [Bulk push events are created](../user/admin_area/settings/push_event_activities_limit.md) if it surpasses that value. |
 | `push_event_hooks_limit`                 | integer          | no                                   | Number of changes (branches or tags) in a single push to determine whether webhooks and services fire or not. Webhooks and services aren't submitted if it surpasses that value. |

doc/user/project/merge_requests/browser_performance_testing.md

@@ -93,7 +93,7 @@ that you can later download and analyze. This implementation always takes the la
 Browser Performance artifact available. If [GitLab Pages](../pages/index.md) is enabled,
 you can view the report directly in your browser.
 
-You can also customize the jobs with environment variables:
+You can also customize the jobs with CI/CD variables:
 
 - `SITESPEED_IMAGE`: Configure the Docker image to use for the job (default `sitespeedio/sitespeed.io`), but not the image version.
 - `SITESPEED_VERSION`: Configure the version of the Docker image to use for the job (default `14.1.0`).
@@ -118,7 +118,7 @@ performance:
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/27599) in GitLab 13.0.
 
 You can configure the sensitivity of degradation alerts to avoid getting alerts for minor drops in metrics.
-This is done by setting the `DEGRADATION_THRESHOLD` variable. In the example below, the alert only shows up
+This is done by setting the `DEGRADATION_THRESHOLD` CI/CD variable. In the example below, the alert only shows up
 if the `Total Score` metric degrades by 5 points or more:
 
 ```yaml
@@ -189,7 +189,7 @@ GitLab version:
 
 - In GitLab 12.4 [a job template was made available](https://gitlab.com/gitlab-org/gitlab/blob/master/lib/gitlab/ci/templates/Verify/Browser-Performance.gitlab-ci.yml).
 - In 13.2 the feature was renamed from `Performance` to `Browser Performance` with
-additional template variables. The job name in the template is still `performance`
+additional template CI/CD variables. The job name in the template is still `performance`
 for compatibility reasons, but may be renamed to match in a future iteration.
 - For 11.5 to 12.3 no template is available and the job has to be defined manually as follows:
 

doc/user/project/merge_requests/code_quality.md

@@ -89,7 +89,7 @@ scans your source code for code quality issues. The report is saved as a
 that you can later download and analyze.
 
 It's also possible to override the URL to the Code Quality image by
-setting the `CODE_QUALITY_IMAGE` variable. This is particularly useful if you want
+setting the `CODE_QUALITY_IMAGE` CI/CD variable. This is particularly useful if you want
 to lock in a specific version of Code Quality, or use a fork of it:
 
 ```yaml
@@ -235,12 +235,12 @@ was chosen as an operational decision by the runner team, instead of exposing `d
 
 ### Disabling the code quality job
 
-The `code_quality` job doesn't run if the `$CODE_QUALITY_DISABLED` environment
-variable is present. Please refer to the environment variables [documentation](../../../ci/variables/README.md)
+The `code_quality` job doesn't run if the `$CODE_QUALITY_DISABLED` CI/CD variable
+is present. Please refer to the CI/CD variables [documentation](../../../ci/variables/README.md)
 to learn more about how to define one.
 
-To disable the `code_quality` job, add `CODE_QUALITY_DISABLED` as a custom environment
-variable. This can be done:
+To disable the `code_quality` job, add `CODE_QUALITY_DISABLED` as a custom CI/CD variable.
+This can be done:
 
 - For the whole project, [in the project settings](../../../ci/variables/README.md#create-a-custom-variable-in-the-ui)
   or [CI/CD configuration](../../../ci/variables/README.md#create-a-custom-variable-in-the-ui).
@@ -364,7 +364,7 @@ After the Code Quality job completes:
 
 In [GitLab 13.6 and later](https://gitlab.com/gitlab-org/ci-cd/codequality/-/issues/10),
 it is possible to generate an HTML report file by setting the `REPORT_FORMAT`
-variable to `html`. This is useful if you just want to view the report in a more
+CI/CD variable to `html`. This is useful if you just want to view the report in a more
 human-readable format or to publish this artifact on GitLab Pages for even
 easier reviewing.
 

doc/user/project/merge_requests/load_performance_testing.md

@@ -104,8 +104,8 @@ An example configuration workflow:
 
 1. Set up GitLab Runner to run Docker containers, like the
    [Docker-in-Docker workflow](../../../ci/docker/using_docker_build.md#use-the-docker-executor-with-the-docker-image-docker-in-docker).
-1. Configure the default Load Performance Testing CI job in your `.gitlab-ci.yml` file.
-   You need to include the template and configure it with variables:
+1. Configure the default Load Performance Testing CI/CD job in your `.gitlab-ci.yml` file.
+   You need to include the template and configure it with CI/CD variables:
 
    ```yaml
    include:
@@ -153,7 +153,7 @@ but it can be extended to work with [review apps](../../../ci/review_apps) or
 [dynamic environments](../../../ci/environments) with a few extra steps.
 
 The best approach is to capture the dynamic URL in a [`.env` file](https://docs.docker.com/compose/env-file/)
-as a job artifact to be shared, then use a custom environment variable we've provided named `K6_DOCKER_OPTIONS`
+as a job artifact to be shared, then use a custom CI/CD variable we've provided named `K6_DOCKER_OPTIONS`
 to configure the k6 Docker container to use the file. With this, k6 can then use any
 environment variables from the `.env` file in scripts using standard JavaScript,
 such as: ``http.get(`${__ENV.ENVIRONMENT_URL}`)``.