Move PowerStats service sepolicy to powerstats am: 041f4263d1 am: fa8bc7c2dc am: 4154d58a62

Original change: https://android-review.googlesource.com/c/platform/hardware/google/pixel-sepolicy/+/1428229

Change-Id: Ifeaf1d9b96fb5890f8f40ff11b7ae93dc15d6d7e