Do not attempt installing reform-qcacld2 in the background if inside chroot

If this script is not run on a real system with a real init process but
in a container-like chroot environment, then creating these background
processes without waiting for their completion will leave zombie
processes behind which hog resources like /dev/null and thus prevent the
container software from cleanly un-mounting bind-mounts as they may have
been created for /dev/null. We cannot reliably detect whether the
container manager will automatically wait for and reap zombie processes,
so as a hacky workaround, we just make this script a no-op if it is
started inside a chroot environment.