bootstat: remove the only caller of liblogcat.

We need to make progress both on adding the real interface for battery
level and cleaning up logging. This stands in the way of both.

Bug: http://b/77725702
Test: builds
Change-Id: Ia457e497606c2c7965d6895baebb26eef17857c9
Merged-In: Ia457e497606c2c7965d6895baebb26eef17857c9