Revert "webauthn: update field trial config to test M128 enclave mode."

This reverts commit d133cdad1a47ee5559b3edc52c5af70985ea8450.

Reason for revert: Test failing on win-arm64-rel-ready

https://ci.chromium.org/ui/p/chrome/builders/ci/win-arm64-rel-ready/34046/test-results

Original change's description:
> webauthn: update field trial config to test M128 enclave mode.
>
> Change-Id: I0597ee3c358d98e3e603c41ddf378363fea1a4b3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5747051
> Commit-Queue: Adam Langley <agl@chromium.org>
> Reviewed-by: Ken Buchanan <kenrb@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1335491}

Change-Id: Iec90bcfd80ff3605d1dd391535f6944300677afb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5753224
Auto-Submit: Owen Min <zmin@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Owners-Override: Owen Min <zmin@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1335513}