Remove feature flag docs for Confluence service

With the feature flags removed in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/36781, this
change updates the documentation to reflect this.

https://gitlab.com/gitlab-org/gitlab/-/issues/220934
https://gitlab.com/gitlab-org/gitlab/-/issues/228731

doc/api/services.md

@@ -496,12 +496,6 @@ GET /projects/:id/services/emails-on-push
 ## Confluence service
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/220934) in GitLab 13.2.
-> - It's deployed behind a feature flag, disabled by default.
-> - It's disabled on GitLab.com.
-> - It's able to be enabled or disabled per-project
-> - It's not recommended for production use.
-> - To use it in GitLab self-managed instances, ask a GitLab administrator to
-    [enable it](#enable-or-disable-the-confluence-service-core-only). **(CORE ONLY)**
 
 Replaces the link to the internal wiki with a link to a Confluence Cloud Workspace.
 
@@ -535,31 +529,6 @@ Get Confluence service settings for a project.
 GET /projects/:id/services/confluence
 ```
 
-### Enable or disable the Confluence service **(CORE ONLY)**
-
-The Confluence service is under development and not ready for production use. It is
-deployed behind a feature flag that is **disabled by default**.
-[GitLab administrators with access to the GitLab Rails console](../administration/feature_flags.md)
-can enable it for your instance. The Confluence service can be enabled or disabled per-project
-
-To enable it:
-
-```ruby
-# Instance-wide
-Feature.enable(:confluence_integration)
-# or by project
-Feature.enable(:confluence_integration, Project.find(<project id>))
-```
-
-To disable it:
-
-```ruby
-# Instance-wide
-Feature.disable(:confluence_integration)
-# or by project
-Feature.disable(:confluence_integration, Project.find(<project id>))
-```
-
 ## External Wiki
 
 Replaces the link to the internal wiki with a link to an external wiki.

doc/user/project/integrations/overview.md

@@ -28,7 +28,7 @@ Click on the service links to see further configuration instructions and details
 | Buildkite | Continuous integration and deployments | Yes |
 | [Bugzilla](bugzilla.md) | Bugzilla issue tracker | No |
 | Campfire | Simple web-based real-time group chat | No |
-| Confluence | Replaces the link to the internal wiki with a link to a Confluence Cloud Workspace. Service is behind a feature flag, disabled by default ([see details](../../../api/services.md#enable-or-disable-the-confluence-service-core-only)). | No |
+| [Confluence](../../../api/services.md#confluence-service) | Replaces the link to the internal wiki with a link to a Confluence Cloud Workspace | No |
 | Custom Issue Tracker | Custom issue tracker | No |
 | [Discord Notifications](discord_notifications.md) | Receive event notifications in Discord | No |
 | Drone CI | Continuous Integration platform built on Docker, written in Go | Yes |