Merge "libprocessgroup: Use WriteStringToFd for WriteFileAction" am: 9dfff25365 am: 18173b1e54 am: c314f7c8aa am: 3c4948bfce

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1895031

Change-Id: I99bea8d261d92a8f82a073eb16240bb591a97261