Make CloneDatabase error out on shared tables.

Due to the way prefixes are handled, this doesn't work properly.

Make it quit early to prevent confusion. I don't think there's
many people who need shared table support, so I don't know if
its worth the effort to actually fix.

Bug: 65654
Change-Id: I6cd701998fc9066d8c7a4fc86d93a4282cc7f9bd