ImageService: Skip Sync-the-feature check for bookmarks

...if kReplaceSyncPromosWithSignInPromos or
kEnableBookmarkFoldersForAccountStorage are enabled.
When either of these flags are enabled, then callers themselves check
the Sync-the-feature state *if necessary*, see crrev.com/c/5346717.

Note that ImageServiceConsentHelper still checks whether the user has
opted in to upload bookmarks - this just doesn't require
Sync-the-feature anymore.

Bug: 40067770
Change-Id: I3a6759fed635145062827f182795afabf8d7f082
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5353813


Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1271061}