Simplify blob sidecar availability checker

[tbenr]

blobs get from EL are marked as valid (trust assumption on EL)

fixes #8740

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[tbenr]

since i forgot to do this marking i think the way I did it is a bit error prone. I'll change it.

[zilm13]

I will join Mehdi feedback:

• if some validation was not performed I expect that we want to run it now
• if it means that it was actually performed but failed it's confusing
• I'm not sure on extending base BlobSidecar class, maybe better make some wrapper? It would be cleaner.
• I'm happy with split kzg+inclusion / signature

[zilm13]

Have not checked tests, yet (starting)

[zilm13]

Great work!
LGTM
Worth run on some test nodes before merging into master.

[tbenr]

Worth run on some test nodes before merging into master.

I run an historical sync test (mainnet) , I'll run more tests (mainnet and local)

[tbenr]

I actually forgot this:

discovered during tests :)

[tbenr]

@zilm13 take a look to latest commit. Testing session was fine, historical sync, forward symc, chain follow.

[zilm13]

@tbenr loooks good, the only nit, it maybe better to mark it as validated in if, by to your decision.