fix: handle undecodable MultiSend data in event processing

[falvaradorodriguez]

get_contracts_from_data assumed the calldata of every EXECUTED_MULTISIG_TRANSACTION was a multiSend call. MultiSend.from_transaction_data only catches ValueError, so when the data starts with the multiSend selector (0x8d80ff0a) but its body isn't a valid argument (truncated, corrupt, or a selector collision), eth_abi raised DecodingError/OverflowError and crashed the queue consumer (InsufficientDataBytes in staging). Now we catch (ValueError, DecodingError, ArithmeticError), log a warning and return an empty set; the event is still processed via its to address.