Remove pre-Fulu restriction on blobs endpoint

[geoknee]

Thinned down version of #18780

Now the Fusaka fork is some time in the past, we don't need to support historical behaviour of beacon providers, and can just model them as supporting the new beacon blobs endpoint at all times.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.62%. Comparing base (4de6002) to head (cc1437d).
⚠️ Report is 2034 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #18810      +/-   ##
===========================================
+ Coverage    73.54%   77.62%   +4.07%     
===========================================
  Files          190      135      -55     
  Lines        11318     7288    -4030     
===========================================
- Hits          8324     5657    -2667     
+ Misses        2848     1631    -1217     
+ Partials       146        0     -146     

Flag	Coverage Δ
cannon-go-tests-64	?
contracts-bedrock-tests	77.62% <ø> (+0.59%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 57 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.