fix: Fix the battery icon using the wrong color in split screen.

See http://b/423390143#comment13 header (2).

Bug: 423390143
Test: DarkIconInteractorTest
Test: manually reproduce issue by entering split screen with
      light theme app on left and dark theme app on right;
      observe battery icon is correctly white.
Flag: com.android.systemui.status_bar_dark_icon_interactor_mixed_fix
Change-Id: Ibc0b56be9d02f46dd2fc8260e1764ee0517aef85