Fix feature category for the TestsController

This controller incorrectly inherited continuous_integration as the
feature category from the
Projects::Pipelines::ApplicationController. This fixes that so the
metrics for this controller show up on the testing group's dashboard.

app/controllers/projects/pipelines/tests_controller.rb

@@ -6,6 +6,8 @@ module Projects
       before_action :authorize_read_build!
       before_action :builds, only: [:show]
 
+      feature_category :code_testing
+
       def summary
         respond_to do |format|
           format.json do