Settings: Remove leftover reference to AppOps tabs

PS1: After removing AppOps tabs there were still references to a text array
in res/values/arrays.xml and AppOpsSummary.java

Change-Id: Icee1cad1f7ff91f9d0c5c962f52ea424afa64f4e
Settings: Replace low battery warning icon with Google warning icon

PS1: replace string in PowerUsageSummary to point to new icon
and replace drawables with Google drawables

Change-Id: Ie123feabb7a74feb61f4cd732ae9b1326099a1e7