chore: rework the remaining shapes flagged by the sixth independent audit - #1889

Summary

Follow-up to the sixth independent audit of the #1835 removal claims. Reworks the last flagged shapes: the DNSOutgoing.__init__ field initialization sequence (0.83 token similarity to the 2009 constructor), the one surviving five word prose run, and the docstrings still scoring 0.60-0.65 against removed text.

Details

• DNSOutgoing.__init__ and _reset_for_next_packet now set fields in rule generated order: alphabetical within each group, except the four section lists, which keep RFC 1035 section 4.1 order (question, answer, authority, additional) with a citation comment. Assignment order is behavior neutral and the struct layout is owned by the .pxd, which is untouched.
• The known answer suppression docstring loses the shared "is at least half of" phrase and now matches the strict comparison in the code ("more than half our TTL"), still citing RFC 6762 section 7.1.
• The two write() rdata docstrings and the _set_created_ttl docstring are deleted rather than reworded: the four sibling write() overrides carry no docstring, so deletion is the consistent form and removes the similarity entirely.
• async_wait's docstring is reworded away from the removed 2009 phrasing.
• The probe pacing loop the same audit flagged is restructured separately in refactor: compute probe pacing from fresh clock reads #1888.

Test plan

• full compiled test suite after REQUIRE_CYTHON=1 rebuild: 516 passed
• pre-commit clean