relay: rework kill->kick forwarding to send from the sender network's subservers
relay: rework kill->kick forwarding to send from the sender network's subservers

This makes the kick message a lot neater.

Before:
* net1.relay has kicked GL/net1 from #test ((net2.relay) KILL FWD from GL/net2: test)

After:
* net2.relay has kicked GL/net1 from #test (KILL FWD from GL/net2: test)

GLolol/PyLink