Fix cycle analytics code after improving serializers

lib/gitlab/cycle_analytics/base_stage.rb

@@ -13,7 +13,7 @@ module Gitlab
       end
 
       def as_json
-        AnalyticsStageSerializer.new.represent(self).as_json
+        AnalyticsStageSerializer.new.represent(self)
       end
 
       def title

lib/gitlab/cycle_analytics/code_event_fetcher.rb

@@ -18,7 +18,7 @@ module Gitlab
       private
 
       def serialize(event)
-        AnalyticsMergeRequestSerializer.new(project: @project).represent(event).as_json
+        AnalyticsMergeRequestSerializer.new(project: @project).represent(event)
       end
     end
   end

lib/gitlab/cycle_analytics/issue_event_fetcher.rb

@@ -16,7 +16,7 @@ module Gitlab
       private
 
       def serialize(event)
-        AnalyticsIssueSerializer.new(project: @project).represent(event).as_json
+        AnalyticsIssueSerializer.new(project: @project).represent(event)
       end
     end
   end

lib/gitlab/cycle_analytics/plan_event_fetcher.rb

@@ -37,7 +37,7 @@ module Gitlab
       def serialize_commit(event, st_commit, query)
         commit = Commit.new(Gitlab::Git::Commit.new(st_commit), @project)
 
-        AnalyticsCommitSerializer.new(project: @project, total_time: event['total_time']).represent(commit).as_json
+        AnalyticsCommitSerializer.new(project: @project, total_time: event['total_time']).represent(commit)
       end
     end
   end

lib/gitlab/cycle_analytics/review_event_fetcher.rb

@@ -15,7 +15,7 @@ module Gitlab
       end
 
       def serialize(event)
-        AnalyticsMergeRequestSerializer.new(project: @project).represent(event).as_json
+        AnalyticsMergeRequestSerializer.new(project: @project).represent(event)
       end
     end
   end

lib/gitlab/cycle_analytics/stage_summary.rb

@@ -16,7 +16,7 @@ module Gitlab
       private
 
       def serialize(summary_object)
-        AnalyticsSummarySerializer.new.represent(summary_object).as_json
+        AnalyticsSummarySerializer.new.represent(summary_object)
       end
     end
   end

lib/gitlab/cycle_analytics/staging_event_fetcher.rb

@@ -23,7 +23,7 @@ module Gitlab
       private
 
       def serialize(event)
-        AnalyticsBuildSerializer.new.represent(event['build']).as_json
+        AnalyticsBuildSerializer.new.represent(event['build'])
       end
     end
   end