net/wireguard-tools: Revert kldunload from rc.d scripts

Unloading if_wg(4) kmod was added to rc.d scripts to make sure that a
service restart also reload the kernel module.

Now we don't have frequent updates anymore and the wireguard-kmod port
will soon be gone but people using this script face issues in VNET jails.

This commit reverts 562d171b9dacad8f63e6e4a45035824b10b59341

PR: 274428
Reported by: vedad@kajtaz.net