Vulkan: Add missing command pool reset. We were still calling destroy in checkCompletedCommands. We can instead call reset. May not significantly impact performance. Bug: angleproject:3489 Change-Id: I61a2cb154faac56dc78a49678dd822d81ce16ad2 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1647029 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tobin Ehlis <tobine@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>