Replace Banzai based label rendering in VSA

This change replaces the Banzai based, slow label rendering in value
stream analytics. This improves the performance of the value_streams
endpoint.

Changelog: performance

app/serializers/analytics/cycle_analytics/stage_entity.rb

@@ -3,6 +3,10 @@
 module Analytics
   module CycleAnalytics
     class StageEntity < Grape::Entity
+      include ActionView::Context
+      include LabelsHelper
+      include ActionView::Helpers::TagHelper
+
       expose :title
       expose :hidden
       expose :legend
@@ -43,10 +47,20 @@ module Analytics
         html_description(object.end_event)
       end
 
+      # Avoid including ActionView::Helpers::UrlHelper
+      def link_to(*args)
+        ActionController::Base.helpers.link_to(*args)
+      end
+
       private
 
       def html_description(event)
-        Banzai::Renderer.render(event.markdown_description, { group: object.group, project: nil })
+        options = {}
+        if event.label_based?
+          options[:label_html] = render_label(event.label, link: '', small: true, tooltip: true)
+        end
+
+        content_tag(:p) { event.html_description(options).html_safe }
       end
     end
   end

ee/lib/gitlab/analytics/cycle_analytics/stage_events/issue_label_added.rb

@@ -13,8 +13,8 @@ module Gitlab
             :issue_label_added
           end
 
-          def markdown_description
-            s_("CycleAnalyticsEvent|%{label_reference} label was added to the issue") % { label_reference: label.to_reference }
+          def html_description(options)
+            s_("CycleAnalyticsEvent|%{label_reference} label was added to the issue") % { label_reference: options.fetch(:label_html) }
           end
 
           def object_type

ee/lib/gitlab/analytics/cycle_analytics/stage_events/issue_label_removed.rb

@@ -13,8 +13,8 @@ module Gitlab
             :issue_label_removed
           end
 
-          def markdown_description
-            s_("CycleAnalyticsEvent|%{label_reference} label was removed from the issue") % { label_reference: label.to_reference }
+          def html_description(options = {})
+            s_("CycleAnalyticsEvent|%{label_reference} label was removed from the issue") % { label_reference: options.fetch(:label_html) }
           end
 
           def object_type

ee/lib/gitlab/analytics/cycle_analytics/stage_events/merge_request_label_added.rb

@@ -13,8 +13,8 @@ module Gitlab
             :merge_request_label_added
           end
 
-          def markdown_description
-            s_("CycleAnalyticsEvent|%{label_reference} label was added to the merge request") % { label_reference: label.to_reference }
+          def html_description(options)
+            s_("CycleAnalyticsEvent|%{label_reference} label was added to the merge request") % { label_reference: options.fetch(:label_html) }
           end
 
           def object_type

ee/lib/gitlab/analytics/cycle_analytics/stage_events/merge_request_label_removed.rb

@@ -13,8 +13,8 @@ module Gitlab
             :merge_request_label_removed
           end
 
-          def markdown_description
-            s_("CycleAnalyticsEvent|%{label_reference} label was removed from the merge request") % { label_reference: label.to_reference }
+          def html_description(options)
+            s_("CycleAnalyticsEvent|%{label_reference} label was removed from the merge request") % { label_reference: options.fetch(:label_html) }
           end
 
           def object_type

lib/gitlab/analytics/cycle_analytics/stage_events/stage_event.rb

@@ -19,7 +19,7 @@ module Gitlab
             raise NotImplementedError
           end
 
-          def markdown_description
+          def html_description(options = {})
             self.class.name
           end
 

spec/support/shared_examples/lib/gitlab/cycle_analytics/event_shared_examples.rb

@@ -9,7 +9,7 @@ RSpec.shared_examples_for 'value stream analytics event' do
   it { expect(described_class.identifier).to be_a_kind_of(Symbol) }
   it { expect(instance.object_type.ancestors).to include(ApplicationRecord) }
   it { expect(instance).to respond_to(:timestamp_projection) }
-  it { expect(instance).to respond_to(:markdown_description) }
+  it { expect(instance).to respond_to(:html_description) }
   it { expect(instance.column_list).to be_a_kind_of(Array) }
 
   describe '#apply_query_customization' do