Optimize log filter matching and trigger allocation (#6419)

* chain/ethereum: Use O(1) edge lookup in EthereumLogFilter

Replace all_edges() linear scan with contains_edge() and edge_weight()
in matches() and requires_transaction_receipt().

* chain/ethereum: Pre-allocate triggers Vec in parse_log_triggers

Replace flat_map(...).collect() with explicit loops and a pre-sized Vec
to avoid repeated reallocations.