Revert "Move native battery percent to system_settings"

This reverts commit 018daacf2f57b0bdded0dccd555711e8d2fc0381.
Revert "battery level text: edit settings to match https://github.com/rascarlo/android_frameworks_base/commit/fcc6ca48f753009f653cbb8b8d84bb6772530b8e"

This reverts commit 53642c4c21b0a70caf674a503dbe8462844b5f66.