Enable deployment frequency graphs by default

This commit updates the `deployment_frequency_charts` feature flag to be
enabled by default.

ee/app/helpers/ee/graph_helper.rb

@@ -6,7 +6,7 @@ module EE
 
     override :should_render_deployment_frequency_charts
     def should_render_deployment_frequency_charts
-      return false unless ::Feature.enabled?(:deployment_frequency_charts, @project)
+      return false unless ::Feature.enabled?(:deployment_frequency_charts, @project, default_enabled: true)
       return false unless @project.feature_available?(:project_activity_analytics)
 
       can?(current_user, :read_project_activity_analytics, @project)

ee/changelogs/unreleased/nfriend-enable-deployment-frequency-graphs-by-default.yml

+---
+title: Add deployment frequency charts to CI/CD Analytics page
+merge_request: 51338
+author:
+type: added

ee/config/feature_flags/development/deployment_frequency_charts.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/296893
 milestone: '13.8'
 type: development
 group: group::release
-default_enabled: false
+default_enabled: true