[Feature flag] Rollout of `block_anonymous_global_searches` and `advanced_global_search_for_limited_indexing`

What

Remove the :feature_name feature flag ...

Owners

• Team: Global Search
• Most appropriate slack channel to reach out to: #g_global_search
• Best individual to reach out to: @DylanGriffith

Expectations

What are we expecting to happen?

What might happen if this goes wrong?

What can we monitor to detect problems with this?

Roll Out Steps

• Enable on staging
• Test on staging
• Coordinate a time to enable the flag with #production and #g_delivery on slack.
• Enable on GitLab.com by running chatops command in #production
• 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 as well as adding the docs removed in !41041 (f59512fc)
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel