Convert performance_bar_stats to an ops feature flag

What

Remove the :performance_bar_stats feature flag introduced in !48149 (merged)

Owners

• Team: Plan
• Most appropriate slack channel to reach out to: #g_plan
• Best individual to reach out to: jprovaznik

Expectations

What are we expecting to happen?

Data are logged in performance_bar_log_json.log

What might happen if this goes wrong?

Increased load due to async job which proceses peek stats (in case there would be extreme amount of these stats) - which is low chance - we delete peek redis data after 30 minutes.

What can we monitor to detect problems with this?

Sidekiq job (app/workers/gitlab_performance_bar_stats_worker.rb), size of performance_bar_log_json.log file

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.

This feature is enabled/disabled globally.

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 --project=gitlab-org/gitlab performance_bar_stats false