chg: test: Deduplicate and unify named.conf.j2 in system tests

named.conf.j2 templates were unified across the system test code base.

Changes with possible functional impact:
- use a common template for root.hints which use `a.root-server.nil. IN A 10.53.0.1`: this may change the TTL of the record - I don't think the affected tests rely on it
- add missing `*-source` options: unless the tests are intentionally about testing `*-source` options, I believe it's just a copy-paste omission
- add missing `listen-on-v6 { none; }`: not specifying those is misconfiguration. tests that want IPv6 must explicitly specify which IPv6 to use
- set the `port @PORT@` if missing: not setting the port is clearly not intended, as that would default to port 53, which shouldn't be used in tests (with the exception of a couple of live internet tests)

Changes without any functional impact:
- drop `directory .` default option
- drop `recursive yes` default option
- drop `notify yes` default option
- replace space indentation with tabs
- introduce jinja2 templates for shared options and root hints and use those

Closes #5398

Merge branch '5398-named-conf-boilterplate' into 'main'

See merge request isc-projects/bind9!12474