Change kFullServerCard to not synced in IsSyncedWalletCard

Full server cards (i.e. unmasked server cards) are no longer persisted
in Chrome - that is, they are not and cannot be stored on disk. They
exist only as a temporary cached state post unmasked, used if a card is
re-filled on the same page to avoid unnecessary re-authentication. As
such, they should no longer be considered a syncable card type by
AutofillWalletMetadataSyncBridge.

Bug: 40939195
Change-Id: I5c38153a7e7d7632d0a3fddbcb90b1248aa9ddb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5829084


Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Olivia Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/main@{#1349431}