Revert "Convert Standalone Builders to chromium wrappers"

This reverts commit 2be761ae0434470139671d5ee0d87d7ee95b27b9.

Reason for revert: Breaks presubmit builder due to incorrect
recipe.

Bug: 385317083
Original change's description:
> Convert Standalone Builders to chromium wrappers
>
> Converts the experimental standalone Dawn builders to use the wrappers
> provided by the @chromium-luci package. This allows us to fully define
> builders src-side instead of having to split them between the Dawn repo
> and the build repo.
>
> Tests are still defined using the older buildbot JSON approach since
> we want to keep the Swarming dimensions in sync with Chromium's. We may
> be able to roll in Starlark-defined dimensions at some point in the
> future, but the JSON approach should work until that is demonstrated
> to work.
>
> Should be landed in conjunction with crrev.com/c/6808555 to fully move
> the standalone Dawn builders into the Dawn repo.
>
> Bug: 385317083
> Change-Id: I818299ffc1e66a8f9ab946fb1177fe039a654565
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/256094
> Reviewed-by: Garrett Beaty <gbeaty@google.com>
> Commit-Queue: dan sinclair <dsinclair@chromium.org>
> Reviewed-by: dan sinclair <dsinclair@chromium.org>
> Auto-Submit: Brian Sheedy <bsheedy@google.com>

TBR=bsheedy@google.com,dsinclair@chromium.org,dawn-scoped@luci-project-accounts.iam.gserviceaccount.com,gbeaty@google.com

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 385317083
Change-Id: Ic62d74480fe3f9f32e885c97c0825acbfd12fe3e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/256334
Commit-Queue: Brian Sheedy <bsheedy@google.com>
Reviewed-by: Brian Sheedy <bsheedy@google.com>
Reviewed-by: James Price <jrprice@google.com>