[Feature flag] codequality_mr_diff - Enable codequality diff on merge request

What

Remove the :codequality_mr_diff feature flag ...

this will enable the front end feature #267612 (closed) to be visible.

Owners

• Team: Testing
• Most appropriate slack channel to reach out to: #g_testing
• Best individual to reach out to: @shampton, @morefice, @jheimbuck_gl

Expectations

What are we expecting to happen?

When an MR introduces new code quality degradations for a file...

show a badge in the file's header in the MR diff

What might happen if this goes wrong?

The diff report would not show up on the merge request.

What can we monitor to detect problems with this?

If we can monitor the API for response times that should be sufficient (or load time on the page even better).

Beta groups/projects

If applicable, any groups/projects that are happy to have this feature turned on early. Some organizations may wish to test big changes they are interested in with a small subset of users ahead of time for example.

• gitlab-org/gitlab-com groups

Roll Out Steps

• Enable on staging (/chatops run feature set codequality_mr_diff true --staging)
• Test on staging
• Ensure that documentation has been updated
• Enable on GitLab.com for individual groups/projects listed above and verify behaviour (/chatops run feature set --project=gitlab-org/gitlab codequality_mr_diff true)
• Enable on GitLab.com by running chatops command in #production (/chatops run feature set codequality_mr_diff true)
• Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry !63461 (merged)
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel