test: one hub for the blocks-only and orphan-tx journey

[rearden-grok]

Summary

• Fold fifteen peer_tests.rs units (item 4 of the journey-fold index) into peer_blocksonly_and_orphan_tx. That is one regtest hub, one peer book, and one 130-block pad, where before there were fifteen store opens, most with their own 100-block pad.
• The story runs with relay off first. A tx or wtx inv from an ordinary peer disconnects. A sendraw INVs once it is unbroadcast, never to block-relay, and then serves. A relay@ whitelisted peer's tx is kept and INV'd to the other inbound. A type-0 getdata is ignored while the tip block still serves.
• A block then confirms those txs. Relay-on (tip-mode entry) purges them.
• With relay on: forced INVs skip block-relay, already-seen, feefilter, and isolated local-origin peers. Inbound waits 30s even for unbroadcast, never gets a tx older than its connection, and idle ticks neither clone nor rescan. GetData serves only an announced or reorged-back tx, and a sendraw after a +300s jump neither INVs nor serves. An orphan parks on a tokio worker, and the missing-parent GETDATA waits NONPREF+TXID.
• Pushed up from the old units: the reorg beat disconnects a real block (invalidate_block) instead of calling reorg_reaccept. The relay-off "remove is a no-op" check is now a real block plus the relay-on purge. Peers disconnect through unregister, which also erases their orphans.
• Second commit: drop MempoolHub::evict_live_txids. testmempoolaccept stopped calling it in b6d8b09, and the folded test was its last caller.
• TESTING.md gains the catalog row. The compact journey row now points at this journey for the worker park and park-not-reject logs. The ephemeral-broadcast plan's Red/Verify commands name the journey.

Three throwaway mutations in peer.rs each turn the journey red: no inv_gen_floor check, serve every mempool getdata, force-announce ignores feefilter.

Test plan

• cargo test -p rbitcoin-net --lib peer_blocksonly_and_orphan_tx (repeated runs; ~2s)
• cargo fmt --all -- --check, cargo clippy --workspace --all-targets -- -D warnings, cargo deny check, ./scripts/ast-grep.sh, cargo test --workspace --quiet, ./scripts/ci-os-smoke.sh
• Required CI: qc, test, windows, macos, coverage

🤖 Generated with Claude Code

[bobberb]

@reardencode I got much better sustained performance on catch up (I'm at 400K now)