Replace #2637
It may be better to start with small changes rather than writing overcomplicated scripts.

1. Use validator guide helpers to generate the execution payload for on_merge_block tests

See run_get_execution_payload_with_mock_engine_get_payload.

• Comparing to [WIP] Mock Engine API req/resp in tests #2637, this PR doesn't output the block production API calls logs.
• Using validator guide get_execution_payload would improve our test coverage a bit. 🙂 We can also create validator guide unit tests later in other PRs.

2. Fork choice rule test format updates

This PR changes the existing fork choice tests output:

1. Add one more layer to the execution steps.
   • e.g., previous {'attestation': attestation_0x<attestation_root>} is now {'on_attestation': {'attestation': 'attestation_0x<attestation_root>'}}
   • it allows us to add more description to the on_block step.
2. Change the pow_block output
   • make it only shows when get_pow_block helper is called.
   • e.g.,

     - on_block:
         ...
         block: block_0x6f0e0d6d65481fc1142bde4234b8537a502facc3b26168046cfcecd95e6bdc8a
         get_pow_block:
           input: {block_hash: 0x922ef34b6ca455c5d13de0ac5db0f6d7c1c26adfa026141a2e086fb155deb6b4}
           output: {result: pow_block_0x006a9edb9f8316403009d1cf96c21907ddfafe86c5701c49cd0d57abab2a8a7b}

3. Output mocking engine_executePayload request and response with on_block
   • e.g., if an on_block step triggers process_execution_payload and engine_executePayload:

     - on_block:
         ...
         process_execution_payload:
           engine_api:
             request:
               method: engine_executePayload
               params:
                 parentHash: '0x006a9edb9f8316403009d1cf96c21907ddfafe86c5701c49cd0d57abab2a8a7b'
                 coinbase: '0x1212121212121212121212121212121212121212'
                 stateRoot: '0x0000000000000000000000000000000000000000000000000000000000000000'
                 receiptRoot: '0x6e6f207265636569707473206865726500000000000000000000000000000000'
                 logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'
                 random: '0xdadadadadadadadadadadadadadadadadadadadadadadadadadadadadadadada'
                 blockNumber: 1
                 gasLimit: 0
                 gasUsed: 0
                 timestamp: 12
                 extraData: 0x
                 baseFeePerGas: 0
                 blockHash: '0x15c1774a93c7a216ca89fb27245b0dec9c6a8a8ebab162ffcbe80861de87e4fc'
                 transactions: []
             response:
               error: false
               result: {status: VALID}

   • Client team can use the request fields to verify if the request is as expected.
   • Client team can use the response fields as the return value of the given APIs.

Minor fixes

• Fix default prepare_payload parameters in setup.py
• Refactor build_empty_execution_payload