Deprecate Snapshot build

Existing snapshot code will no longer work from VNDK deprecation, but it
can give confusion to users if we keep code for the snapshot - and it
adds complexity on existing code while it is not in use. This change
removes all snapshot definition except host snapshot and its usage.

Bug: 330100430
Bug: 332986564
Test: AOSP CF build succeeded
Change-Id: Ieb6fa43d5e38315c662ce997bc305b744b367c24