Enable builds queue limit by default

This removes the gitlab_ci_builds_queue_limit
feature flag enabling the builds queue limit
for all instances

Changelog: changed

app/services/ci/register_job_service.rb

@@ -182,13 +182,7 @@ module Ci
     end
 
     def max_queue_depth
-      @max_queue_depth ||= begin
-        if Feature.enabled?(:gitlab_ci_builds_queue_limit, runner, default_enabled: true)
-          MAX_QUEUE_DEPTH
-        else
-          ::Gitlab::Database::MAX_INT_VALUE
-        end
-      end
+      MAX_QUEUE_DEPTH
     end
 
     # Force variables evaluation to occur now

config/feature_flags/development/gitlab_ci_builds_queue_limit.yml

----
-name: gitlab_ci_builds_queue_limit
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/54579
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/323201
-milestone: '13.10'
-type: development
-group: group::continuous integration
-default_enabled: true

spec/services/ci/register_job_service_spec.rb

@@ -839,34 +839,13 @@ module Ci
         stub_const("#{described_class}::MAX_QUEUE_DEPTH", 2)
       end
 
-      context 'when feature is enabled' do
-        before do
-          stub_feature_flags(gitlab_ci_builds_queue_limit: true)
-        end
-
-        it 'returns 409 conflict' do
-          expect(Ci::Build.pending.unstarted.count).to eq 3
-
-          result = described_class.new(specific_runner).execute
-
-          expect(result).not_to be_valid
-          expect(result.build).to be_nil
-        end
-      end
-
-      context 'when feature is disabled' do
-        before do
-          stub_feature_flags(gitlab_ci_builds_queue_limit: false)
-        end
-
-        it 'returns a valid result' do
-          expect(Ci::Build.pending.unstarted.count).to eq 3
+      it 'returns 409 conflict' do
+        expect(Ci::Build.pending.unstarted.count).to eq 3
 
-          result = described_class.new(specific_runner).execute
+        result = described_class.new(specific_runner).execute
 
-          expect(result).to be_valid
-          expect(result.build).to eq pending_job_3
-        end
+        expect(result).not_to be_valid
+        expect(result.build).to be_nil
       end
     end