Vulkan: Use QueueSerial to track RefCountedEvent garbage RefCountedEvent garbage are only used on one command buffer, so it is a single QueueSerial is enough to track it. Bug: b/336844257 Change-Id: Icafeee722fe19f41dd863a2e6aca6ddd981d28a4 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5529952 Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com> Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>