[Battery] Update fill colors

They were incorrectly defined backwards, using the darker GM600 fill
when the frame was lighter, and GM500 when the frame was darker.

This change corrects the inversion (using lighter fill when the frame is
lighter), and also increases the instensity, moving from GM600 -> GM700
and GM500 -> GM400

Test: manual
Bug: 314812750
Flag: ACONFIG com.android.settingslib.flags.new_status_bar_icons DEVELOPMENT
Change-Id: I45c2a9b0dff5bff03c4a86582807cd2048fc59d8