Test improvement tracking issue

[jimmygchen]

• Reduce number of blobs used in tests to speed up CI #8194
• Run tests only on recent forks
• Skip tests that aren't relevant for the fork when using fork_from_env, e.g. prune_blobs_across_fork_boundary shouldn't need to be ran for every fork, is only relevant between deneb - fulu
• Optimize slow tests - there are many that takes > 120s
• Fake Kzg Impl for some tests to speed things up

[jimmygchen]

Re fake Kzg Impl, we can even turn it on in test + debug mode, that also avoids the stackoverflow issue with blobs while running tests in debug mode - and we still have the real verification covered with release tests on CI