Put iteration charts behind correct feature flag

It requires both iteration_charts (to get chart data) and
burnup charts (so chart component doesn't render old burndown chart)

ee/app/assets/javascripts/iterations/components/iteration_report.vue

@@ -220,7 +220,7 @@ export default {
         :namespace-type="namespaceType"
       />
       <burn-charts
-        v-if="glFeatures.burnupCharts"
+        v-if="glFeatures.iterationCharts && glFeatures.burnupCharts"
         :start-date="iteration.startDate"
         :due-date="iteration.dueDate"
         :iteration-id="iteration.id"

ee/app/controllers/groups/iterations_controller.rb

@@ -5,6 +5,7 @@ class Groups::IterationsController < Groups::ApplicationController
   before_action :authorize_show_iteration!, only: [:index, :show]
   before_action :authorize_create_iteration!, only: [:new, :edit]
   before_action do
+    push_frontend_feature_flag(:iteration_charts, group)
     push_frontend_feature_flag(:burnup_charts, group)
   end
 

ee/app/controllers/projects/iterations/inherited_controller.rb

@@ -4,6 +4,7 @@ class Projects::Iterations::InheritedController < Projects::ApplicationControlle
   before_action :check_iterations_available!
   before_action :authorize_show_iteration!
   before_action do
+    push_frontend_feature_flag(:iteration_charts, project)
     push_frontend_feature_flag(:burnup_charts, project)
   end
 

ee/app/controllers/projects/iterations_controller.rb

@@ -4,6 +4,7 @@ class Projects::IterationsController < Projects::ApplicationController
   before_action :check_iterations_available!
   before_action :authorize_show_iteration!
   before_action do
+    push_frontend_feature_flag(:iteration_charts, project)
     push_frontend_feature_flag(:burnup_charts, project)
   end