Remove self monitoring feature flag
What does this MR do?
This removes the feature flag for the self monitor feature that allows the tracking of metrics of a GitLab instance
This depends on the following issues: #42612 (closed) #121719 (closed) #121721 (closed) #198048 (closed)
Original issue: #198511 (closed)
Does this MR meet the acceptance criteria?
Conformity
Edited by 🤖 GitLab Bot 🤖