Scale battery text size in shade in low display sizes.

This is the same behaviour as that of status bar icons (see b/413620149)

Bug: 438705602
Bug: 413620149
Flag: com.android.systemui.fix_shade_header_wrong_icon_size
Test: atest com.android.systemui.statusbar.pipeline.battery.ui.viewmodel.BatteryViewModelTest
Test: Locally tested "Until x:xx" text scaling in lower display sizes.
Change-Id: I021d2fab230d7aca737c7cd63f5f29ce92300046