chg: test: Convert all named.conf in system tests to jinja2

Replace all the `named.conf*.in` files to use jinja2 templates instead. This makes it possible to drop the `copy_setports` function, makes room for further `setup.sh` cleanup, and prepares for future de-duplication of the configs (common settings as well as shared configs within one test dir).

Merge branch 'nicki/convert-to-jinja2-templates' into 'main'

See merge request isc-projects/bind9!11332