[Sync] Remove SyncDoNotCommitBookmarksWithoutFavicon feature toggle

The feature toggle was enabled by default in M85.

Bug: None
Change-Id: Idad5ef2f8623f324bea6df50872e6d92ef18ecfe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2661395


Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Rushan Suleymanov <rushans@google.com>
Cr-Commit-Position: refs/heads/master@{#850536}