[3.6] CP: don't clear domain RAM under a published SharedDomains (#23046)

[lupin012]

Problem. RPC read views keep a DomainReader pointing at the published SD's in-memory domain maps. The background-commit teardown (bgSD.Close() → mem.Close() → ClearRam()) emptied those maps while readers were still using them. A receipt read of the in-flight block then missed silently, fell back to the request's pre-commit tx, and ReceiptAsOf zero-filled the miss: GetReceiptsGasUsed returned GasUsed=0 for every tx of the head block, and eth_feeHistory reward percentiles were silently wrong. Latest-state reads could likewise fall back to the previous block's state mid-request.

Fix. TemporalMemBatch.Close no longer clears the in-memory domain maps: they go to the GC once the last reference drops. With that, ClearRam had no production caller left and is removed entirely — the batch has a single lifetime (write, maybe publish, close-and-drop) and no API can clear the maps under readers. The one internal test that used clear-and-reuse now mirrors what cmd/integration actually does today: a fresh SharedDomains per batch.

Tests. New TestClose_KeepsDomainRamForReaders (red before the fix, green after). One existing assert updated: a post-teardown view now keeps serving the published head instead of falling back to its own tx.