Revert "Revert "healthd: don't report fake data for battery-less devices""

This reverts commit 1bc572df.

The presubmit test that (incorrectly) fails on the original commit
has been marked @FlakyTest and a bug is failed on Assistant.

Bug: 34507420
Test: manual: gce_x6_phone (no battery or charger),
      boots and stays booted, inspect properties,
      presubmit tests on gce_x86
Change-Id: I5509bf5de9fceffdd5fd8abc3f1f4f6101119248