Refactor AP1 ExtData Checks

[StephenButtolph]

Why this should be merged

Personally, I find the current code hard to reason about.

• The current code has multiple cases where AP1 is checked.
• The pre-AP1 check (which is required even after the chains have advanced past AP1) is only enforced for Fuji and Mainnet, even though all chains really would need this check.
• The pre-AP1 checks have a control flow based on untrusted data (rather than having the control flow based on trusted data).

How this works

1. Refactors the pre-AP1 checks to perform validation based on the known extDataHashes rather than based on the claimed extData.
2. Enforces all non-Fuji/Mainnet chains with pre-AP1 blocks to not have any extData.
3. Combined both !rules.IsApricotPhase1 cases into a single block.

How this was tested

CI / visual inspection.

Need to be documented?

No.

Need to update RELEASES.md?

No

[ceyonur]

i think removal of this what caused UTs to fail as we don't have extDataHashes for UTs.