Use APPLY text button for grid picker am: 82c09c5e89 am: 3a7b68037c am: 104d4151b1

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/14957119

Change-Id: I96bdf304131e9403c239997fa462a6e19b2de904