[Feature flag] Enable Runner Registration Control by default for self-managed GitLab

Overview

The [Runner Registration Control feature] for GitLab administrators was released in 14.1 behind a feature flag. Based on comments from customers and the user community, we should now consider enabling this feature as a default option on self-managed GitLab.

Proposal

Remove the runner_registration_control feature flag.

Edited Jul 15, 2022 by Darren Eastman