[BUG] ensure that listeners from disabled proxies are correctly unbound.

[BUG] ensure that listeners from disabled proxies are correctly unbound.

There is a problem when an instance is marked "disabled". Its ports are
still bound but will not be unbound upon termination. This causes processes
to accumulate during soft restarts, and might even cause failures to restart
new ones due to the inability to bind to the same port.

The ideal solution would be to bind all ports at the end of the configuration
parsing. An acceptable workaround is to unbind all listeners of disabled
proxies. This is what the current patch does.