fix(app): use proper MaxWithdrawalsPerBlock for x/evmengine to prevent potential issues

[taeguk]

Practically, there would be no issue even if we set MaxWithdrawalsPerBlock to 0 because fallback logic in event procedures would not actually be called. We already have proper verification logic on the contract side (ValidatorManager.sol), so registerValidator and depositCollateral would always succeed.

However, setting MaxWithdrawalsPerBlock properly would be better practice and prevent potential issues. Therefore, I will set MaxWithdrawalsPerBlock to 32.
I don't think it would be a problem if we use different values for MaxWithdrawalsPerBlock and WithdrawalLimit. I will use a hard-coded value (32) for MaxWithdrawalsPerBlock, while WithdrawalLimit will be managed in evmvalidator's parameters. We might use a value less than or equal to 32 for the WithdrawalLimit, so hard-coding MaxWithdrawalsPerBlock should not be an issue.