[9.20] chg: test: Replace dns.query module with isctest.query

The `dns.query.udp` and `dns.query.tcp` methods are [prone to timeouts](https://gitlab.isc.org/isc-projects/bind9/-/jobs/4785053); their `isctest.query` equivalents should be used in system tests instead.

Backport of MR !9560

Merge branch 'backport-mnowak/convert-dns-query-udp-and-tcp-to-isctest-query-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!9574