Drop supplementary groups for child zygotes. am: 7c8779c0 am: 80cfa981 am: 75f35b04 am: 89a122db

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11691614

Change-Id: I77a996085b1790b75bd51c28cfadba15ee2caabb