ethapi: fix merge transition in eth_simulate

[deffrian]

When we call eth_simulate with a pre-merge block(or genesis), all simulate blocks are marked as pre-merge.
For example calling this on hoodi network

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_simulateV1",
  "params": [
    {
      "blockStateCalls": [
        {
          "stateOverrides": {
            "0xc200000000000000000000000000000000000000": {
              "code": "0x6080604052348015600e575f80fd5b505f3660605f49600149600249604051602001602b93929190605d565b6040516020818303038152906040529050915050805190602001f35b5f819050919050565b6057816047565b82525050565b5f606082019050606e5f8301866050565b607960208301856050565b608460408301846050565b94935050505056fea26469706673582212206284471b14925acedc8cf50c596b6850cfda0372471ee8893750f3e61bf3778164736f6c634300081a0033"
            }
          },
          "calls": [
            {
              "from": "0xc000000000000000000000000000000000000000",
              "to": "0xc200000000000000000000000000000000000000"
            }
          ]
        }
      ],
      "returnFullTransactions": true
    },
    "0x0"
  ]
}

yeilds

{
  "returnData": "0x",
  "logs": [],
  "gasUsed": "0x2255100",
  "status": "0x0",
  "error": {
    "message": "invalid opcode: PUSH0",
    "code": -32015
  }
}

But all blocks on hoodi should have Shanghai activated

For reference, result from Nethermind(we set difficulty to 0 in the block header):

{
  "status": "0x1",
  "returnData": "0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "gasUsed": "0x53f6",
  "logs": []
}

[deffrian]

This is a copy-past from consensus/beacon/consensus.go. Maybe there is a better way to check if a block is post-merge?

[s1na]

Please add a comment here and give hoodi's genesis block having difficulty 0x1 as an example.