Update VulkanMemoryTest after adding context flush After adding context flushing to the memory allocation fallbacks in a previous CL (https://crrev.com/c/4787949), some tests in the VulkanMemoryTest suite no longer test the success path of the fallback to wait for submitted commands to finish. * Updated AllocateVMAImageAfterFreeing2DGarbageWhenDeviceOOM * The test now uses an additional allocation and draw after the first sync, followed by a second sync. During the allocation of the last texture, it would wait to finish the submitted command and free the garbage without flushing the whole context. Bug: b/280304441 Change-Id: Idc583e120b8d9e1cc550f6cba4cb0b2b197e4944 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4860367 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Amirali Abdolrashidi <abdolrashidi@google.com>