The older version of the code was reporting that listeners are going
to be of the same type after reconfiguration when switching from DoT
to HTTPS listener, making BIND abort its executions.

That was happening due to the flaw in logic due to which the code
could consider a current listener and a configuration for the new one
to be of the same type (DoT) even when the new listener entry is
explicitly marked as HTTP.

The checks for PROXY in between the configuration were masking that
behaviour, but when porting it to 9.18 (when there is no PROXY
support), the behaviour was exposed.

Now the code mirrors the logic in 'interface_setup()' closely (as it
was meant to).