Commit transaction synchronously for OnHoldFragment.

We show OnHoldFragment for new conference call, and remove it after updating info. After cl/172475223, the update only happens once and sometimes removing the fragment happens before adding the fragment. Committing synchronously fix the bug.

Test: manual
PiperOrigin-RevId: 174374676
Change-Id: I5337f6592ca2924ed6a089ecaefe00d920f85738
1 file changed