fix coinbase payment edge case

[dvush]

📝 Summary

When the coinbase address is the fee recipient, we exclusively use fee_recipient_balance_diff
since this is the value used by validation nodes

Using fee_recipient_balance_diff may cause block validation failures in certain edge cases

Real Example: If the fee recipient is a contract that sweeps its balance to another address on each call,
and we include a bundle paying directly to coinbase, the fee recipient balance would be 0 causing validation nodes to reject the block

💡 Motivation and Context

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✅ I have completed the following steps:

• Run make lint
• Run make test
• Added tests (if applicable)