flag-metadata: remove skip-service-worker-fetch-handler flag

This CL removes skip-service-worker-fetch-handler from flag-metadata
since the feature is enabled by default and is expired in M123.

Bug: 41494030
Change-Id: Ie554ffb577f675d47132df20ed15e5d8bb58c924
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5417535


Reviewed-by: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Reviewed-by: Shunya Shishido <sisidovski@chromium.org>
Commit-Queue: Keita Suzuki <suzukikeita@google.com>
Cr-Commit-Position: refs/heads/main@{#1281663}