[Feature flag] Rollout of `vue_notification_dropdown`

What

Remove the :vue_notification_dropdown feature flag.

Owners

• Team: groupoptimize
• Most appropriate slack channel to reach out to: #g_manage_optimize
• Best individual to reach out to: @wortschi

Expectations

What are we expecting to happen?

User's should be able to change their notifications settings on the following pages via the newly introduces Vue component:

• project settings
• group settings
• user notification settings

What might happen if this goes wrong?

The feature does not work as expected

What can we monitor to detect problems with this?

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/manage/optimize
• gitlab-org/gitlab project
• gitlab-org/gitlab-com groups

Roll Out Steps

• Enable on staging (/chatops run feature set feature_name 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 feature_name true)
• Coordinate a time to enable the flag with the SRE oncall and release managers
  • In #production by pinging @sre-oncall
  • In #g_delivery by pinging @release-managers
• Announce on the issue an estimated time this will be enabled on GitLab.com
• Enable on GitLab.com by running chatops command in #production (/chatops run feature set feature_name true)
• Cross post chatops Slack command to #support_gitlab-com (more guidance when this is necessary in the dev docs) and in your team channel
• Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel

Rollback Steps

• This feature can be disabled by running the following Chatops command:

/chatops run feature set vue_notification_dropdown false