Enable Mac/Intel experiment Enables the Mac/Intel experimental tester to test on Mac 15.4. Bug: chromium:414760990 Change-Id: I504a57f4ce81bcabecce50f17410f92ae572a5be Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6514293 Auto-Submit: Brian Sheedy <bsheedy@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>