Prevent tools from using ports which clash with named instances in system tests
Windows is affected by #905 (closed) and #925 (closed), too:
- https://gitlab.isc.org/isc-private/bind9/-/jobs/571917
- https://gitlab.isc.org/isc-private/bind9/-/jobs/572857
Since isc_net_getudpportrange()
on Windows returns a hardcoded range of ports, the simplest solution is to raise ISC_NET_PORTRANGELOW
to something like 32768.