Merge branch 'ag-refactor-group-summary' into 'master'

app/models/cycle_analytics/group_level.rb

...ntrollers/analytics/cycle_analytics/summary_controller.rb

ee/app/models/analytics/cycle_analytics/group_level.rb

...b/gitlab/analytics/cycle_analytics/group_stage_summary.rb

...ib/gitlab/analytics/cycle_analytics/summary/group/base.rb

.../gitlab/analytics/cycle_analytics/summary/group/deploy.rb

...ics/cycle_analytics/summary/group/deployment_frequency.rb

...b/gitlab/analytics/cycle_analytics/summary/group/issue.rb

...lers/analytics/cycle_analytics/summary_controller_spec.rb

...lab/analytics/cycle_analytics/group_stage_summary_spec.rb

ee/spec/models/analytics/cycle_analytics/group_level_spec.rb

lib/gitlab/cycle_analytics/group_stage_summary.rb

lib/gitlab/cycle_analytics/summary/group/base.rb

lib/gitlab/cycle_analytics/summary/group/deploy.rb

...lab/cycle_analytics/summary/group/deployment_frequency.rb

lib/gitlab/cycle_analytics/summary/group/issue.rb