Merge branch 'ce-7472-epics-autocomplete' into 'master'

CE port: Remove instance autocomplete_service variable

See merge request gitlab-org/gitlab-ce!22847

app/controllers/projects/autocomplete_sources_controller.rb

 # frozen_string_literal: true
 
 class Projects::AutocompleteSourcesController < Projects::ApplicationController
-  before_action :load_autocomplete_service, except: [:members]
-
   def members
     render json: ::Projects::ParticipantsService.new(@project, current_user).execute(target)
   end
 
   def issues
-    render json: @autocomplete_service.issues
+    render json: autocomplete_service.issues
   end
 
   def merge_requests
-    render json: @autocomplete_service.merge_requests
+    render json: autocomplete_service.merge_requests
   end
 
   def labels
-    render json: @autocomplete_service.labels_as_hash(target)
+    render json: autocomplete_service.labels_as_hash(target)
   end
 
   def milestones
-    render json: @autocomplete_service.milestones
+    render json: autocomplete_service.milestones
   end
 
   def commands
-    render json: @autocomplete_service.commands(target, params[:type])
+    render json: autocomplete_service.commands(target, params[:type])
   end
 
   def snippets
-    render json: @autocomplete_service.snippets
+    render json: autocomplete_service.snippets
   end
 
   private
 
-  def load_autocomplete_service
-    @autocomplete_service = ::Projects::AutocompleteService.new(@project, current_user)
+  def autocomplete_service
+    @autocomplete_service ||= ::Projects::AutocompleteService.new(@project, current_user)
   end
 
   def target