fix(network): remove every address book entry for a banned peer IP

[jiehuo100net]

Motivation

Closes #11134.

After a peer IP is banned, an address book entry for that same IP on a different port could
survive the ban and then stay at the front of the reconnection order for the lifetime of the
process, producing a burst of attempted to add a banned peer addr to address book warnings on
every crawl cycle. This was observed on Mainnet shortly after NU6.3 activation, when the wave of
misbehavior bans made it easy to hit.

Solution

Three changes in zebra-network, matching the three defects in the issue:

1. AddressBook::update() scans the whole book when removing a banned IP's entries.
   by_addr is an OrderedMap keyed by reconnection order, not grouped by IP, so entries for one
   IP can be separated by entries for other IPs. The previous
   skip_while(ip != banned).take_while(ip == banned) scan stops at the first entry for a
   different IP, leaving any later same-IP entry behind. Replaced with a filter over all keys.

2. reconnection_peers() skips banned IPs. A surviving entry was selected as a candidate on
   every crawl; the ban check at the top of update() then rejected the resulting UpdateAttempt,
   so the entry was never marked AttemptPending and its position never changed. Filtering
   bans_by_ip here means a banned IP cannot be handed out even if an entry does reach the book.

3. The rejected-change log moved from warn to debug. Remote peers can gossip a banned
   address at any time, so the volume of this message was effectively chosen by them.

Tests

One regression test in zebra-network/src/address_book/tests/vectors.rs,
ban_removes_every_entry_for_the_banned_ip. It builds a book where an unrelated IP sorts between
two entries that share the banned IP, and asserts that ordering before doing anything else —
with contiguous entries the test would pass against the old code and prove nothing. After the ban
it asserts the book holds exactly the unrelated entry, and that reconnection_peers() yields
exactly the unrelated address.

Negative controls, reverting the real implementation rather than reimplementing it, one change at a
time:

Implementation state	ban_removes_every_entry_for_the_banned_ip
Both changes (this PR)	pass
Change 1 reverted	FAIL
Change 2 reverted	pass
Both reverted (main)	FAIL

Change 1 is pinned directly by the test. Change 2 is defence in depth: with change 1 in place the
surviving-entry state is not reachable through update(), so no test can isolate it. That is why
the two earlier tests are now one — the second could only fail when the first also failed.

Gates run locally on this branch, all in debug:

• cargo fmt --all -- --check — clean
• cargo clippy --workspace --all-targets -- -D warnings — clean, for both the default-release-binaries
  and the proptest-impl lightwalletd-grpc-tests zebra-checkpoints feature sets
• cargo clippy -p zebra-network --all-targets -- -D warnings and cargo build -p zebra-network,
  for each of the four feature combinations CI runs per crate — clean
• cargo test -p zebra-network --lib — 216 passed, 0 failed (217 before the two tests became one)
• .github/scripts/validate-pr-changelogs.sh <merge-base> HEAD true fix false — exit 0

Specifications & References

• Banned peer leaves a "zombie" address-book entry that spams attempted to add a banned peer addr WARNs every crawl cycle #11134 — the issue, including the Mainnet log signature and the three-defect breakdown.
• feat(network): Track misbehaving peer connections and ban them past a threshold #9201 — introduced the misbehavior ban tracking and this warning.

Follow-up Work

The issue's third defect also has a structural half that this PR does not touch: when update()
returns None, CandidateSet::next() returns before the
MIN_OUTBOUND_PEER_CONNECTION_INTERVAL sleep, so queued crawler demand drains in a tight loop.
With the two changes above, a ban no longer drives that loop. The general fix belongs with the
CandidateSet/AddressBook refactor in #1976, as the issue notes.

AI Disclosure

• No AI tools were used in this PR
• AI tools were used: Claude Code, for the code, the tests, and this description. All of it was
  reviewed and verified by hand, including the negative-control runs in the table above.

PR Checklist

• The PR title follows conventional commits format: type(scope): description
• The PR follows the contribution guidelines.
• This change was discussed in an issue or with the team beforehand.
• The solution is tested.
• The documentation and changelogs are up to date.

[oxarbitrage]

Fix looks good, thanks!

Verbosity can be reduced a bit, i left some comments.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-08-05 15:05 UTC · Rule: batched · triggered by rule move to any queue if GitHub Rulesets are satisfied
• ✅ Checks passed · on draft merge queue: checking main (da29357) and #11173 together #11190
• ✅ Merged — 2026-08-05 15:51 UTC · at fd2dc730c5806d1a84bde73e586361077fc5afcc · merge

This pull request spent 46 minutes 18 seconds in the queue, including 45 minutes 25 seconds running CI.

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