Crop avatar to circle when syncing from Contacts.

This ensures that photos synced to the Android user icon from the
Me Contact, by the ProfileUpdateReceiver, are cropped to a circle.

This matches the behaviour when images are selected using the
avatar picker.

Bug: 256827004
Test: Manual, build & flash, sync photo, observe in lockscreen.
Change-Id: If1abf110b74a3892a5cfb76ee344be79c867feed