[Feature flag] Enable new Prometheus settings section in operations page

What

Remove the :settings_operations_prometheus_service feature flag.

Added via !24727 (merged) (see #200019 (closed)).

Owners

• Team: ~"group::health"
• Most appropriate slack channel to reach out to: #g_monitor_health
• Best individual to reach out to: @splattael

Expectations

What are we expecting to happen?

What might happen if this goes wrong?

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.

• https://gitlab.com/mikolaj_wawrzyniak/autodevops-docker-app (enabled via https://gitlab.com/gitlab-com/gl-infra/feature-flag-log/-/issues/450)

Roll Out Steps

• Enable on staging (/chatops run feature set feature_name true --staging) via https://gitlab.com/gitlab-com/gl-infra/feature-flag-log/-/issues/449
• Test on staging
• Ensure that documentation has been updated
• Enable on GitLab.com for individual groups/projects listed above and verify behaviour via https://gitlab.com/gitlab-com/gl-infra/feature-flag-log/-/issues/450
• Coordinate a time to enable the flag with #production and #g_delivery on slack.
• 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