<!-- Title suggestion: [Feature flag] Cleanup <feature-flag-name> -->

## Summary

This issue is to clean up the `<feature-flag-name>` feature flag, after the feature flag has been enabled by default for an appropriate amount of time in production.

<!-- Short description of what the feature is about and link to relevant other issues. Ensure to note if the feature will be removed completely or will be productized-->

## Owners

- Team: GitLab Runner
- Most appropriate Slack channel to reach out to: `#g_runner`
- Best individual to reach out to: NAME
- PM: NAME

## Stakeholders

<!--
Are there any other stages or teams involved that need to be kept in the loop?

- Name of a PM
- The Support Team
- The Delivery Team
-->

## Expectations

### What might happen if this goes wrong?

Please list here all the steps that must be taken if something goes wrong:

- Any MRs that need to be rolled back?
- Communication that needs to happen?
- What are some things you can think of that could go wrong in the context of GitLab Runner and the existing setups?
- What settings needs to be changed back, e.g. Feature Flag, or `config.toml` settings ?

### Cleaning up the feature flag

In most use cases, removing a feature flag will be a breaking change. This breaking change must be planned in accordance with the GitLab's policy on breaking changes.

<!-- The checklist here is to help stakeholders keep track of the feature flag status -->
- [ ] Specify in the issue description if this feature will be removed completely or will be productized as part of the Feature Flag cleanup
- [ ] Create a merge request to remove `<feature-flag-name>` feature flag. Ask for review and merge it.
  - [ ] Remove all references to the feature flag from the codebase.
  - [ ] Remove the documentations for the feature from the repository.
  - [ ] Remove the documentations for the feature from related repository (GitLab, GitLab Runner Helm Chart, GitLab Runner Operator).
- [ ] Ensure that the cleanup MR has been deployed at the code cutoff.
- [ ] Close [the feature issue](ISSUE LINK) to indicate the feature will be released in the current milestone.
- [ ] Close this feature flag cleanup issue.

/label ~"feature flag" ~"section::ci" ~"group::runner" ~"DevOps::verify" ~"Category:Runner Core" ~"runner::core"
<!-- Uncomment the appropriate type label
/label ~"type::feature" ~"feature::addition"
/label ~"type::maintenance"
/label ~"type::bug"
-->
