Do not specify a workSource when setting a delayed alarm so that the

alarm can still wake the device up when the device is idle as the
AlarmManager.FLAG_ALLOW_WHILE_IDLE_UNRESTRICTED flag indicates.

Bug: 188302603,193260066
Test: presubmits
Change-Id: I2cc8f7bb49d626644f9b4257b04f4f8ea5fc3d2f