Refactor double calculation of intrinsic gas

[marcindsobczak]

Avoid calculating intrinsic gas twice - at validation and at execution:
https://github.com/NethermindEth/nethermind/blob/master/src/Nethermind/Nethermind.Consensus/Validators/TxValidator.cs#L121

[Mohansai-M]

Hi @marcindsobczak can I take this