Update MWPS feature spec per change to remove source branch default.

spec/features/merge_requests/merge_when_pipeline_succeeds_spec.rb

@@ -42,7 +42,7 @@ feature 'Merge When Pipeline Succeeds', :feature, :js do
           click_button "Merge when pipeline succeeds"
 
           expect(page).to have_content "Set by #{user.name} to be merged automatically when the pipeline succeeds."
-          expect(page).to have_content "The source branch will be removed."
+          expect(page).to have_content "The source branch will not be removed."
           expect(page).to have_selector ".js-cancel-auto-merge"
           visit_merge_request(merge_request) # Needed to refresh the page
           expect(page).to have_content /enabled an automatic merge when the pipeline for \h{8} succeeds/i
@@ -101,7 +101,7 @@ feature 'Merge When Pipeline Succeeds', :feature, :js do
         click_link 'Merge when pipeline succeeds'
 
         expect(page).to have_content "Set by #{user.name} to be merged automatically when the pipeline succeeds."
-        expect(page).to have_content "The source branch will be removed."
+        expect(page).to have_content "The source branch will not be removed."
         expect(page).to have_link "Cancel automatic merge"
       end
     end