Commonize pixelstats uevent sepolicies into pixel-specific sepolicy folder am: a66c550b55 am: 640101ea01

Original change: https://android-review.googlesource.com/c/platform/hardware/google/pixel-sepolicy/+/1646895

Change-Id: I9e635b59805cad25b4ff986969aeb7d300d4526f