Don't show the alternates dialog for GAL contacts

There's a bug in the chips code that causes this to show either no
alternates, or a different person, which is scaring people.

The proper future fix is to store some more information about GAL
contacts so we can do a proper lookup.

Bug: 11535331

Change-Id: Id8b6fc834446afe33bd6ec4e99b3d2b75b985bde