Remove track_ai_metrics_in_usage_data feature flag

Changelog: removed

config/feature_flags/beta/track_ai_metrics_in_usage_data.yml

----
-name: track_ai_metrics_in_usage_data
-feature_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/457504
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/155973
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/466664
-milestone: '17.1'
-group: group::optimize
-type: beta
-default_enabled: false

ee/spec/requests/api/usage_data_spec.rb

@@ -23,10 +23,6 @@
 
       let(:event_name) { 'code_suggestion_shown_in_ide' }
 
-      before do
-        stub_feature_flags(track_ai_metrics_in_usage_data: true)
-      end
-
       it 'triggers AI tracking' do
         expect(Gitlab::Tracking::AiTracking).to receive(:track_event)
                                                   .with(

lib/api/usage_data.rb

@@ -108,9 +108,7 @@ class UsageData < ::API::Base
           .fetch(:additional_properties, Gitlab::InternalEvents::DEFAULT_ADDITIONAL_PROPERTIES)
           .symbolize_keys
 
-        if Feature.enabled?(:track_ai_metrics_in_usage_data) && # rubocop:disable Gitlab/FeatureFlagWithoutActor -- beta
-            !Gitlab::Tracking::AiTracking.track_via_code_suggestions?(event_name, current_user)
-
+        unless Gitlab::Tracking::AiTracking.track_via_code_suggestions?(event_name, current_user)
           Gitlab::Tracking::AiTracking.track_event(event_name, additional_properties.merge(user: current_user))
         end