Commit 1f87331fb moved the known-transaction marking in
`sendPooledTransactionHashes` to after a successful send, so hashes are
not marked known to the peer if the announcement fails to go out.
The sparse blobpool change (d91b71fb3) reintroduced the original
track-before-send ordering when adding the eth/72 packet variant,
causing failed announcements to suppress future re-announcements of the
same hashes to that peer.
This restores the send-first ordering for both eth/71 and eth/72 packet
versions, and adds a regression test covering success and failure paths
on both protocol versions.
## Checklist
- [x] Restored mark-known-after-send for ETH71 and ETH72
- [x] Added `TestSendPooledTransactionHashes` covering success and
closed-pipe failure
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Co-authored-by: Bosul Mun <bsbs8645@snu.ac.kr>
a38a90bc60