[9.20] fix: dev: Fix unitiailized pointer check on getipandkeylist

Function `named_config_getipandkeylist` could, in case of error in the
early code attempting to get the `port` or `tls-port`, make a pointer
check on a non-initialized value. This is now fixed.

Backport of MR !11303

Merge branch 'backport-colin/getipandkeylist-uinitstate' into 'bind-9.20'

See merge request isc-projects/bind9!11306