Skip intermediate merge train test steps

Removes 2 expect statements that might not be seen if the merge train
completes before the test gets to those statements.

Instead we skip to the merge verification, and check that the merge
train pipeline passed.

qa/qa/specs/features/ee/browser_ui/6_release/pipelines_for_merged_results_and_merge_trains_spec.rb

@@ -104,26 +104,24 @@ module QA
         end.visit!
 
         Page::MergeRequest::Show.perform do |show|
-          pipeline_passed = Support::Retrier.retry_until(max_attempts: 5, sleep_interval: 5) do
+          pipeline_passed = show.retry_until(max_attempts: 5, sleep_interval: 5) do
             show.has_pipeline_status?(/Merged result pipeline #\d+ passed/)
           end
 
           expect(pipeline_passed).to be_truthy, "Expected the merged result pipeline to pass."
 
           show.merge_via_merge_train
-        end
 
-        expect(page).to have_content('Added to the merge train', wait: 60)
-        expect(page).to have_content('The changes will be merged into master')
+          # It's faster to refresh the page than to wait for the UI to
+          # automatically refresh, so we reload if the merge status
+          # doesn't update quickly.
+          merged = show.retry_until(max_attempts: 5, reload: true, sleep_interval: 5) do
+            show.merged?
+          end
 
-        # It's faster to refresh the page than to wait for the UI to
-        # automatically refresh, so we reload if the merge status
-        # doesn't update quickly.
-        merged = Support::Retrier.retry_until(reload_page: page) do
-          Page::MergeRequest::Show.perform(&:merged?)
+          expect(merged).to be_truthy, "Expected content 'The changes were merged' but it did not appear."
+          expect(show).to have_pipeline_status(/Merge train pipeline #\d+ passed/)
         end
-
-        expect(merged).to be_truthy, "Expected content 'The changes were merged' but it did not appear."
       end
     end
   end