Make `ci_runner_builds_queue_on_replicas` default

Since the feature was validated it can be made
to be default on now.

changelogs/unreleased/make-ci_runner_builds_queue_on_replicas-default.yml

+---
+title: Make `ci_runner_builds_queue_on_replicas` default
+merge_request:
+author:
+type: performance

config/feature_flags/development/ci_runner_builds_queue_on_replicas.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/325723
 milestone: '13.10'
 type: development
 group: group::continuous integration
-default_enabled: false
+default_enabled: true