`CustomGasCalculator.getEdSignatureVerificationSystemContractGasCost()` still returning placeholder value

Ed25519 signatures are cheaper to verify than ECDSA signatures yet somehow there is a 1.5M gas (vs. 3k `ECRCOVER` gas) placeholder value [here](https://github.com/hiero-ledger/hiero-consensus-node/blob/main/hedera-node/hedera-smart-contract-service-impl/src/main/java/com/hedera/node/app/service/contract/impl/exec/gas/CustomGasCalculator.java#L85). 🤔 