Metal: Run multi draw tests Added ANGLE_INSTANTIATE_TEST_COMBINE_3. Used the new macro for multi draw and BVBI tests. Bug: angleproject:6963 Change-Id: If05800f92f670bf21b7ff889a2fb8bb30f62a488 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5106508 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>