BatteryMonitor: support battery health NOT_AVAILABLE from health status

Battery health is supported but there is not enough information to
determine an accurate value  This is a temporary state.

Bug: 276400004
Test: m
Change-Id: I0d422db20c51ef7e9dc4fa904729beda625c9fea
Signed-off-by: Jack Wu <wjack@google.com>