func-tests: adapt tests to zone changes

tests-extra/tests/axfr/bind_knot/test.py

tests-extra/tests/axfr/knot_bind/test.py

tests-extra/tests/axfr/knot_knot/test.py

tests-extra/tests/basic/nsec/test.py

tests-extra/tests/basic/nsec3/test.py

tests-extra/tests/ddns/prereq/test.py

tests-extra/tests/records/obsolete/test.py

tests-extra/tests/zone/load/test.py