Clear pendingAction when pausing PreCallCoordinator

When resumed runNextAction() will assert that pendingAction is null so if there's any it won't be interrupted. When the coordinator is paused all dialogs and pending actions must be discarded. If the pending action is not properly discarded it will still assert when trying to call finish().

Bug: 69069675
Test: PreCallCoordinatorImplTest
PiperOrigin-RevId: 176420108
Change-Id: Ie89bda3621371a105dc58ff02d83812194a1ea0b