Revert "Add the CanvasResourceDefersWaitSyncToken killswitch"

This reverts commit 1821a16e160779d770b5453c8625bc024b569e8d.

Reason for revert: seems to break WebGPU CTS

Original change's description:
> Add the CanvasResourceDefersWaitSyncToken killswitch
>
> This CL removes the immediate SyncToken waiting in WaitSyncToken() in
> order to allow the waiting to be deferred. This change is put behind a
> killswitch CanvasResourceDefersWaitSyncToken in case any existing
> behavior still depends on the immediate waiting.
>
> Enabled-by-default-reason: killswitch
>
> Bug: 40286368
> Change-Id: Icfde2e1ea3be2097fc1bc6e3fe72e375f9d195d9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6975232
> Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
> Commit-Queue: Mingjing Zhang <mjzhang@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1525037}

Bug: 40286368
Change-Id: Ia3e672c3323c9a86402a54446df377d1458fca18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7006161
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Auto-Submit: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1525662}