Remove SSG timeout when SSG is complete

There's no need for a timeout when the SSG is done.

There have been a number of crashes that all seem to start from the
timeout being hit, but it's unclear where the issue is. Removing the
timeout when SSG completes may stop these crashes.

Test: SurfaceSyncGroupContinuousTest
Bug: 302686733
Change-Id: Iaab861d27ed139ba4c71d195ca3d0d98fc1b3d9e