Allow smaller contract calls after a considered mempool tx would hit block limit

[hstove]

In our block building code, we have the following behavior:

• Fetch a bunch of potential transactions from the mempool
• For each transaction, call try_mine_tx
• If one of the contract calls is too big to fit, we set block_limit_behavior to BlockLimitFunction::CONTRACT_LIMIT_HIT
• If block_limit_behavior is CONTRACT_LIMIT_HIT, we don't even try to mine any other considered contract calls

This is problematic, because there are times where a very big transaction would hit this limit, but there are a bunch of smaller transactions that would fit just fine into the block.

We may want to tweak this behavior. We may simply want to "ignore" the big transaction and/or not skip future considered contract calls if we hit CONTRACT_LIMIT_HIT.

[hstove]

Note: I've pushed a branch that contains an integration test replicating this behavior. https://github.com/stacks-network/stacks-core/blob/feat/big-tx-utils/testnet/stacks-node/src/tests/nakamoto_integrations.rs#L10335