Skip slow test on Mac Metal AMD GLSLTest_ES3.ManySamplerFieldsInStructComplex/ES3_Metal takes 38 seconds and causes batch timeouts. Bug: angleproject:440536251 Change-Id: I53ad821bc4da4696609f9b8c0f5cbee1ed94dbd1 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6874571 Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com> Auto-Submit: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>