[dPWAs] Remove IsTrackingMetadata() CHECK in ApplySyncChanges

This CL removes a CHECK in WebAppSyncBridge::ApplySyncChanges() that
sync is actively tracking the sync profile. ApplySyncChanges() is used
in an error state code path when the sync metadata is invalid and needs
to be reset.
See: https://source.chromium.org/search?q=ClientTagBasedModelTypeProcessor::CheckForInvalidPersistedMetadata

Bug: 1418920
Change-Id: I7f628b74db70c6b788c23685906b8e7f3201cef0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4297093
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1111291}