Remove the FF *_unique_users_pushing_mr_ciconfigfile

Full name:
usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile

It was enabled by default for two milestones.

Changelog: other

config/feature_flags/development/usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile.yml

----
-name: usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/54707
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/322166
-milestone: '13.10'
-type: development
-group: group::pipeline authoring
-default_enabled: true

lib/gitlab/usage_data_counters/known_events/common.yml

@@ -356,7 +356,6 @@
   category: pipeline_authoring
   redis_slot: pipeline_authoring
   aggregation: weekly
-  feature_flag: usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile
 # Merge request widgets
 - name: users_expanding_secure_security_report
   redis_slot: secure

lib/gitlab/usage_data_counters/merge_request_activity_unique_counter.rb

@@ -189,7 +189,6 @@ module Gitlab
         end
 
         def track_mr_including_ci_config(user:, merge_request:)
-          return unless Feature.enabled?(:usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile, user, default_enabled: :yaml)
           return unless merge_request.includes_ci_config?
 
           track_unique_action_by_user(MR_INCLUDING_CI_CONFIG_ACTION, user)

spec/lib/gitlab/usage_data_counters/merge_request_activity_unique_counter_spec.rb

@@ -352,14 +352,6 @@ RSpec.describe Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter, :cl
       it_behaves_like 'a tracked merge request unique event' do
         let(:action) { described_class::MR_INCLUDING_CI_CONFIG_ACTION }
       end
-
-      context 'when FF usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile is disabled' do
-        before do
-          stub_feature_flags(usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile: false)
-        end
-
-        it_behaves_like 'not tracked merge request unique event'
-      end
     end
 
     context 'when merge request does not include any ci config change' do