Remove stale webcodecs expectations

Autogenerated CL from running:

//content/test/gpu/unexpected_pass_finder.py --project chrome-unexpected-pass-data --include-internal-builders --remove-stale-expectations --narrow-semi-stale-expectation-scope --num-samples 300 --suite webcodecs --jobs 4

Affected bugs for CL description:

R=rubber-stamper@appspot.gserviceaccount.com

Bug: 1368785
Change-Id: I9a5ef2f5a12d7be27791a5203800195330c699df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4547014
Auto-Submit: chrome-automated-expectation@chops-service-accounts.iam.gserviceaccount.com <chrome-automated-expectation@chops-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1146406}