Wait for repo contents to load async

qa/qa/specs/features/browser_ui/3_create/repository/push_mirroring_over_http_spec.rb

@@ -37,7 +37,7 @@ module QA
         target_project.visit!
 
         Page::Project::Show.perform do |project|
-          expect(project).to have_content('README.md')
+          expect { project.has_file?('README.md') }.to eventually_be_truthy.within(max_duration: 60), "Expected a file named README.md but it did not appear."
           expect(project).to have_content('This is a test project')
         end
       end

qa/qa/specs/features/ee/browser_ui/3_create/repository/pull_mirroring_over_http_spec.rb

@@ -37,7 +37,7 @@ module QA
         target_project.visit!
 
         Page::Project::Show.perform do |project|
-          expect(project).to have_file('README.md')
+          expect { project.has_file?('README.md') }.to eventually_be_truthy.within(max_duration: 60), "Expected a file named README.md but it did not appear."
           expect(project).to have_readme_content('This is a pull mirroring test project')
           expect(project).to have_text("Mirrored from #{masked_url(source_project_uri)}")
         end