Revert "T1087: Firewall on Wireguard Interface implementation"

This reverts commit 51f61991092a163f680e4ec8f122e73f4074ddf9.
It's not how it's done, those templates are generated by a script in
vyatta-cfg-firewall.
If we are planning a firewall overhaul in 1.3.x, there's no reason to
transplant the old approach to new code.