Remove test for battery percent paint being equal to bolt paint

BatteryMeterView used to draw both the charging bolt and the powersave
'+' symbol as the same color. However the plus sign is drawn as
colorError now, so the test isn't needed anymore.

Test: runtest  -x packages/SettingsLib/tests/integ/src/com/android/settingslib/graph/BatteryMeterDrawableBaseTest.java
Change-Id: I014fbc65d96bed727e880ac492913c2e5d50f405
Fixes: 112205156