Fix mistake in conditional + test

This CL fixes a mixup that was in a conditional that determined
what was shown on the battery settings page. Additionally, it adds
a simple test to help ensure that this does not regress in the
future.

Test: Robotest
Bug: 63158794
Change-Id: I8af4843ef6d798b5114c97b2f1b99dd29fa5f412
2 files changed