Trigger the battery_changed broadcast before getting it's extra.

- This is required to make sure that the sticky broadcast does not
  return a null Intent when called in Test.

Bug: 376786616
Test: atest BatteryChangedBroadcastTest
Flag: TEST_ONLY
Change-Id: I58f4e2e63c7711c05324aaac390b7a3baab35ff0