JobScheduler CTS: Correctly run the tests depending on "charging" event.

The previous code used BatteryController.ACTION_CHARGING_STABLE which is an
intent deleted already at Android M. Instead, the new implementation uses
the shell command to fake the battery status and let BatteryController itself
trigger the equivalent broadcase.

Bug: 128656618
Test: CtsJobSchedulerTestCases on Chromebase(w/o batetry), and Pixel
Change-Id: I8d818a050705b0ddafd43bfa48551f7fddab2030
Merged-In: I5758ea3c30653986f4ccccbc4d0d39746b753b63