The sharding team is adding support for multiple databases and in order
for us to have good visibility into performance we'll want to be able to
distinguish between the different databases in our prometheus metrics.

Adding a prometheus label allows us to filter/group by the different
databases.

By default there will only be 1 `db_config_name` which is `primary` by
default. But this is configured by `config/database.yml` and in future
there will be 2 databases called `main` and `ci`.

This MR also ensures the new label is disabled by default to allow us to
introduce this to production in a slightly more controlled way. We opted
to use an environment variable instead of feature flag in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/66885 because it's
too expensive to query the databases so frequently to check the feature
flag value.

Remove unwanted trailing spaces

See merge request gitlab-org/gitlab!67651

Add test steps for group access tokens

See merge request gitlab-org/gitlab!67656

Remove `GitlabSchema#execute`, and small tidy ups related to max limits

See merge request gitlab-org/gitlab!67590

Resolve "Add missing traversal hierarchy_order specs"

See merge request gitlab-org/gitlab!67575

Add false-positive info of Vulnerability in GraphQL query

See merge request gitlab-org/gitlab!66960

Remove cluster_image_scanning from approval_project_rules table

See merge request gitlab-org/gitlab!67272

Add docs metadata check to Lefthook configuration

See merge request gitlab-org/gitlab!59832

Add crosslinks to the CI/CD permissions

See merge request gitlab-org/gitlab!67394

Also share logic between Lefthook and lint-doc.sh script.

Fix CVE docs badges

See merge request gitlab-org/gitlab!67724

Blob refactor: Add ability to lock/unlock a blob

See merge request gitlab-org/gitlab!67408

Remove unused vulnerability report aside code

See merge request gitlab-org/gitlab!67644

Remove scan_execution_policy_ui feature flag

See merge request gitlab-org/gitlab!67642

Add issue type filtering to issue boards (behind ff) [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!67194

Add experiment routes to robots.txt

See merge request gitlab-org/gitlab!67535

Merge branch '334569-docs-links-refactor-on-follow-up-pass-for-renaming-usage-ping-data-to-service-ping-data' into 'master'

Refactor documentation links source for Service Ping disabled component

See merge request gitlab-org/gitlab!67384

Add instructions for integrating Runner and Sentry

See merge request gitlab-org/gitlab!67676

Update the project approval settings section to Vue

See merge request gitlab-org/gitlab!66536

Merge branch 'jnnkl-remove-security_configuration_redesign-and-security_configuration_redesign_ee' into 'master'

Remove security configuration page feature flags

See merge request gitlab-org/gitlab!66842

Add milestone wildcard filters and MR count to issues page refactor

See merge request gitlab-org/gitlab!67438

Update terraform docs naming convention

See merge request gitlab-org/gitlab!67692

Remove yaml_variables from CI config

See merge request gitlab-org/gitlab!67616

Mark completed jobs as successful

See merge request gitlab-org/gitlab!67687

checks: Fix mismatch in `#new_commits()` signature

See merge request gitlab-org/gitlab!67581

Add note about duplicate helm charts to docs

See merge request gitlab-org/gitlab!67640

Update permissions table for dependency proxy

See merge request gitlab-org/gitlab!67639

Improve Dependency Scanning page

See merge request gitlab-org/gitlab!67561