Merge "Move is_system_uid utility from netd.c to netd.h" into main am: fe0d0f6e33

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2808573

Change-Id: I769c88b86d1c4b6f226faa3082b4d269696c9e40
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>