Wait for the delayed power off

The radio power off can be delayed to disconnect data connections
when turning on airplane mode.

If emergency call is requested before the completion of power off
EmergencyStateTracker should wait for the completion of delayed
operation before turning on power again.

Bug: 332680076
Test: atest EmergencyStateTrackerTest
Change-Id: I19732d22076a898969ab1abe600246c67d868ff5