Remove potential duplicate runnable + add logging

This CL removes an existing runnable for showing the low battery
warning if it hasn't finished. Additionally, it adds some logging
to the trigger method to make it possible to debug issues.

Test: PowerUITests still pass
Bug: 111374781
Change-Id: Iaaf6fa8233cc23f2e608a7968dac617eab0d5ce3
2 files changed