Only prevent overlapping SSG if a buffer is going to be synced

In VRI, SSG are sometimes created as a way to notify WMS that a buffer
has been drawn and not always to sync the buffer. In those cases,
there's no need to prevent overlapping syncs since the buffers cannot be
submitted out of order. Only add the safeguard SSG when there's a buffer
getting synced to ensure multiple buffer syncs for the same VRI are
submitted in order.

Test: SurfaceSyncGroupTests SurfaceSyncGroupTest
Bug: 279096620
Bug: 279790175
Change-Id: I77841296297717e413237c183738b9ec9642f1cf