Remove KZG verification from local block production and blobs fetched from the EL

[jimmygchen]

Issue Addressed

#7700

Proposed Changes

As described in title, the EL already performs KZG verification on all blobs when they entered the mempool, so it's redundant to perform extra validation on blobs returned from the EL.

This PR removes

• KZG verification for both blobs and data columns during block production
• KZG verification for data columns after fetch engine blobs call. I have not done this for blobs because it requires extra changes to check the observed cache, and doesn't feel like it's a worthy optimisation given the number of blobs per block.

This PR does not remove KZG verification on the block publishing path yet.

[mergify]

Some required checks have failed. Could you please take a look @jimmygchen? 🙏

[pawanjay176]

Just noting here that we don't really gain anything from kzg verifying blobs returned by the builder when publishing because we have already signed the message by the time we receive the BlobsBundle.

[michaelsproul]

LGTM on the whole!

[mergify]

This pull request has been removed from the queue for the following reason: checks failed.

The merge conditions cannot be satisfied due to failing checks:

• ☑️ local-testnet-success

You can check the last failing draft PR here: #7772.

You may have to fix your CI before adding the pull request to the queue again.
If you update this pull request, to fix the CI, it will automatically be requeued once the queue conditions match again.
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