Fix PoV attack vector for contracts

[athei]

As of right now PoV sites are not reflected as a resource in our FRAME based run times. For fixed functionality pallets this isn't a show stopper because they can be written in a way that users cannot exploit this (BoundedVec etc.).

However every chain that has the contracts pallet might susceptible to this easy exploit: Craft a transaction that calls many contracts that are big in code size but small in weight (they return immediately). This will choke the throughput without causing an appropriate amount of fees.

The current progress of a proper integration into FRAME is tracked in paritytech/polkadot-sdk#398. This might be too late for us as we cannot launch without it. We have multiple possibilities to protect us from that exploit in the meantime:

• Accelerate PoV Benchmarking Tracking Issue polkadot-sdk#398 (the proper solution). We can't do it ourselves because we lack the resources. We would need to beg the frame team ( @shawntabrizi ) to prioritize it.
• Prevent PoV attack vector with minimal viable solution #11272
• Massively restrict the allowed code so that the attack vector no longer exist. The required code size might make the whole thing not viable anymore.

[athei]

This issue is resolved by #11372 for now. The final solution will be delivered through paritytech/polkadot-sdk#398.