[battery][old] make the old tests use the same logic as the view

The bug here is that the old-new icons are no relying on _both_ the
StatusBarRootModernization and NewStatusBarIcons flags.

We could have alternatively deleted these tests, but that doesn't seem
necessary since the code is still there.

Test: BatteryMeterViewTest
Fixes: 406994386
Flag: EXEMPT bugfix relating to the flags in test
Change-Id: I9e1301b07a92ce0556c822a8f9f866ea26cfec67