Remove feature flag deployment_merge_requests_widget once the changes have been confirmed to work well
In !20066 (merged) we are introducing a feature to display explicitly tracked deployments when viewing a merge request, using the data tracking changes introduced in !18755 (merged).
Once these changes have been deployed to GitLab.com and have been confirmed to work well, we should:
- Add a changelog entry for these changes
- Remove the feature flag and make the new behaviour the default behaviour