Remove custom_prometheus_metrics license check

As part of moving the custom metrics feature into Core, remove the
custom_prometheus_metrics license and all its license checks.

ee/app/controllers/ee/projects/prometheus/metrics_controller.rb

@@ -6,11 +6,6 @@ module EE
       module MetricsController
         extend ActiveSupport::Concern
 
-        prepended do
-          before_action :check_custom_metrics_license!,
-            only: [:validate_query, :index, :create, :update, :edit, :destroy]
-        end
-
         def validate_query
           respond_to do |format|
             format.json do
@@ -92,10 +87,6 @@ module EE
 
         private
 
-        def check_custom_metrics_license!
-          render_404 unless project.feature_available?(:custom_prometheus_metrics)
-        end
-
         def prometheus_metric
           @prometheus_metric ||= ::PrometheusMetricsFinder.new(id: params[:id]).execute.first
         end

ee/app/helpers/ee/environments_helper.rb

@@ -27,7 +27,7 @@ module EE
     end
 
     def custom_metrics_available?(project)
-      project.feature_available?(:custom_prometheus_metrics) && can?(current_user, :admin_project, project)
+      can?(current_user, :admin_project, project)
     end
 
     def metrics_data(project, environment)

ee/app/models/license.rb

@@ -59,7 +59,6 @@ class License < ApplicationRecord
     custom_file_templates
     custom_file_templates_for_namespace
     custom_project_templates
-    custom_prometheus_metrics
     cycle_analytics_for_groups
     db_load_balancing
     default_project_deletion_protection

ee/spec/controllers/projects/prometheus/metrics_controller_spec.rb

@@ -14,20 +14,6 @@ describe Projects::Prometheus::MetricsController do
 
     project.add_maintainer(user)
     sign_in(user)
-
-    stub_licensed_features(custom_prometheus_metrics: true)
-  end
-
-  shared_context 'not found' do
-    before do
-      stub_licensed_features(custom_prometheus_metrics: false)
-    end
-
-    it 'renders 404' do
-      subject
-
-      expect(response).to have_gitlab_http_status(:not_found)
-    end
   end
 
   describe 'POST #validate_query' do
@@ -56,21 +42,9 @@ describe Projects::Prometheus::MetricsController do
         expect(response).to have_gitlab_http_status(:accepted)
       end
     end
-
-    context 'without premium license' do
-      subject { post :validate_query, params: project_params(format: :json, query: query) }
-
-      it_behaves_like 'not found'
-    end
   end
 
   describe 'GET #index' do
-    context 'without premium license' do
-      subject { get :index, params: project_params(format: :json) }
-
-      it_behaves_like 'not found'
-    end
-
     context 'with custom metric present' do
       let!(:prometheus_metric) { create(:prometheus_metric, project: project) }
 
@@ -93,14 +67,6 @@ describe Projects::Prometheus::MetricsController do
   end
 
   describe 'POST #create' do
-    context 'without premium license' do
-      let(:metric) { { prometheus_metric: { title: 'title' } } }
-
-      subject { post :create, params: project_params(metric) }
-
-      it_behaves_like 'not found'
-    end
-
     context 'metric is valid' do
       let(:valid_metric) { { prometheus_metric: { title: 'title', query: 'query', group: 'business', y_label: 'label', unit: 'u', legend: 'legend' } } }
 
@@ -126,14 +92,6 @@ describe Projects::Prometheus::MetricsController do
   end
 
   describe 'DELETE #destroy' do
-    context 'without premium license' do
-      let(:metric) { create(:prometheus_metric, project: project) }
-
-      subject { delete :destroy, params: project_params(id: metric.id) }
-
-      it_behaves_like 'not found'
-    end
-
     context 'format html' do
       let!(:metric) { create(:prometheus_metric, project: project) }
 

ee/spec/features/projects/services/prometheus_custom_metrics_spec.rb

@@ -17,8 +17,6 @@ describe 'Prometheus custom metrics', :js do
     project.add_maintainer(user)
     sign_in(user)
 
-    stub_licensed_features(custom_prometheus_metrics: true)
-
     visit(project_settings_integrations_path(project))
 
     click_link('Prometheus')

ee/spec/helpers/ee/environments_helper_spec.rb

@@ -28,7 +28,7 @@ describe EnvironmentsHelper do
         expect(subject).to include(
           'custom-metrics-path' => project_prometheus_metrics_path(project),
           'validate-query-path' => validate_query_project_prometheus_metrics_path(project),
-          'custom-metrics-available' => 'false',
+          'custom-metrics-available' => 'true',
           'alerts-endpoint' => project_prometheus_alerts_path(project, environment_id: environment.id, format: :json),
           'prometheus-alerts-available' => 'true',
           'logs_path' => project_logs_path(project, environment_name: environment.name)
@@ -79,8 +79,6 @@ describe EnvironmentsHelper do
     before do
       project.add_maintainer(user)
 
-      stub_licensed_features(custom_prometheus_metrics: true)
-
       allow(helper).to receive(:current_user).and_return(user)
 
       allow(helper).to receive(:can?)