[builder] Utilize `blockNumberMax` in conditional transations

[dancoombs]

Describe the feature
https://eips.ethereum.org/EIPS/eip-7796

With conditional transactions the options has a blockNumberMax field. We could always set this to current block number + 2. Then we never have to worry about "replacement underpriced" and cancellations. We can just start from scratch if our UO isn't mined in 2 blocks.

[github-actions]

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