params: default to shanghai evm version on local dev nets

[q9f]

Running a local geth --dev environment still defaults to the London-EVM version, whereas most tooling (e.g., Solidity) expects Shanghai by default.

I'm not sure what the long-term plan is with the local devnet, but I found it quite handy to run tests against a local EVM, and now I need Shanghai. 💛

[holiman]

LGTM, curious to see if the tests pass with the change in TestChainConfig

[q9f]

Ok, the idea was good, but the consequences are massive 😆

• I removed Shanghai from the TestChainConfig to avoid opening the can of worms tests I would have to review
• While tinkering with the consensus rules for Clique and Ethash, I realized that it's suboptimal to add features that expect a merged network to a consensus engine that implies no beacon consensus.
• My intermediate conclusion is that we can not and eventually should not add Shanghai to these engines.

This leaves us with the option to either create a custom Shanghai (without EIP 4895) for testing or, better, create a fake beacon-chain consensus for the local devnet.