Fix local domain and non-FQDN configuration

[DL6ER]

What does this implement/fix?

This PR adds two related commits:

• We should only set local=/<domain>/ if there is no conditional forwarding setting (v6 supports multiple reverse lookup servers), otherwise, this creates a harmless but nonetheless needlessly confusing configuration (ad46a1018a27b17e1320998743f08b90287e8059)
• If dns.domainNeeded is set, refuse to send plain domain queries (like laptop) upstream at all. (231a9853bdca5e4dfdbcde40ea17ec3cdcb7ec46)

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

---

By submitting this pull request, I confirm the following:

1. I have read and understood the contributors guide, as well as this entire template. I understand which branch to base my commits and Pull Requests against.
2. I have commented my proposed changes within the code.
3. I am willing to help maintain this change if there are issues with it later.
4. It is compatible with the EUPL 1.2 license
5. I have squashed any insignificant commits. (git rebase)

Checklist:

• [x] The code change is tested and works locally.
• [x] I based my code and PRs against the repositories developmental branch.
• [x] I signed off all commits. Pi-hole enforces the DCO for all contributions
• [x] I signed all my commits. Pi-hole requires signatures to verify authorship
• [x] I have read the above and my PR is ready for review.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pihole-seems-to-be-redirecting-all-local-dns-to-the-internet/68934/20