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

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

Change-Id: Id1cf65f555bf252048bd6cfe1d92661eb35687f6