DEV: Restore RSpec 'documentation' output, but collapse in CI (#26485)

This reverts commit ef895f1c32ad406a37a10137eab38d75bc82bd38 and 57df0d526e2d131d80c878edee27c8b3a0fccfe4, but adds GitHub actions line grouping to the verbose output to reduce scrolling.

lib/turbo_tests/runner.rb

@@ -89,6 +89,8 @@ module TurboTests
         start_regular_subprocess(tests, process_id + 1, **subprocess_opts)
       end
 
+      @reporter.start
+
       handle_messages
 
       @reporter.finish