This CL converts remaining @stage instances in the dawn tree to use
the equivalent shorter variant.
Bug: tint:1503
Change-Id: I74594cd68544fbd692f77d4646991d9c27e218f8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/92484
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>