fix: only take non-mempool tx to calculate bundle price

[irrun]

Description

fix: only take non-mempool tx to calculate bundle price

Rationale

In current implementation, when a builder receive a bundle, it will simulate all txs within the bundle. Bundle price = sum( gas price * gas used ) /sum(gas used ) , ensure bundle price > = 1 gwei. It seems not a good solution. Consider the following example:
There is a public mempool tx with 100 gwei, gas usage 21,000 and its a simple transfer tx. A malicious actor can submit a 0 gas price tx to bundle it up with the public mempool tx, this tx has 0 gwei gas price, it can involve very complex smart contract calls and it has a gas usage of 1,000,000.
In that case, it will be (10021000+01000000)/(21000+1000000)=2.05 gwei. This means this bundle can be included by builders and land on chain.
However, the malicious actor is essentially a "free rider" in this scenario, and this actor is able to "exploit" the bundle scoring algorithm and make high-gas-usage tx land on chain for free.

Example

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Changes

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