[Feature flag] Cleanup invite_members_group_modal

Summary

This issue is to cleanup the invite_members_group_modal feature flag, after the feature flag has been enabled by default for an appropriate amount of time in production.

This feature moves the member/group invite experience from a form interaction into a modal, which will give us more flexibility to prompt member/group invitations from a broad spectrum of locations in the product at timely moments in the user journey and limit the disruption users experience today when they need to invite a member or group to a project/group.

The feature has been rolled out to 100% on SaaS as of 2022-01-31 and will roll forward to SM on 2022-02-22.

Owners

• Team: ~"group::expansion"
• Most appropriate slack channel to reach out to: #g_expansion
• Best individual to reach out to: @dstull
• PM: @gdoud

Stakeholders

Expectations

What might happen if this goes wrong?

Cleaning up the feature flag

• Create a merge request to remove invite_members_group_modal feature flag. Ask for review and merge it.
  • Remove all references to the feature flag from the codebase.
    • there are changes in the /qa directory here to enable the feature flag that can be removed as well.
  • Remove the YAML definitions for the feature from the repository.
  • Create a changelog entry.
• Ensure that the cleanup MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post.
  • /chatops run auto_deploy status <merge-commit-of-cleanup-mr>
• Close the feature issue to indicate the feature will be released in the current milestone.
• Clean up the feature flag from all environments by running these chatops command in #production channel:
  • /chatops run feature delete invite_members_group_modal --dev
  • /chatops run feature delete invite_members_group_modal --staging
  • /chatops run feature delete invite_members_group_modal
• Close this rollout issue.