Add max epoch activation churn limit for Deneb

[StefanBratanov]

PR Description

• Introduced getValidatorActivationChurnLimit in BeaconStateAccessors and overrode it in BeaconStateAccessorsDeneb
• Added MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT to SpecConfigDeneb to all config files, which have deneb config params already.
• Enabled --Xfork-choice-proposer-boost-uniqueness-enabled to true by default
• Bumped up ref test version to v1.4.0-beta.2-hotfix
• Disabled running the new Deneb fork-choice tests. Raised Support Deneb fork choice reference tests #7539 to support those tests.
• Changed one of the post.ssz in FuzzUtilTest because the post state has changed with the new release - https://github.com/ethereum/consensus-spec-tests/tree/master/tests/minimal/capella/operations/attester_slashing/pyspec_tests/basic_surround

Fixed Issue(s)

fixes #7520

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.

[StefanBratanov]

Waiting for v1.4.0-beta.2 release of consensus-spec-tests

[StefanBratanov]

Waiting for v1.4.0-beta.2 release of consensus-spec-tests

PR updated with latest version

[tbenr]

LGTM. I just want to double-check if there is any config param breaking change.
Like maxPerEpochActivationChurnLimit becomes mandatory and a VC with this PR doesn't start against a BN without this PR

[StefanBratanov]

LGTM. I just want to double-check if there is any config param breaking change. Like maxPerEpochActivationChurnLimit becomes mandatory and a VC with this PR doesn't start against a BN without this PR

Good point. Thanks for checking. Shouldn't break until both are on Deneb in which case, both VC and BN should have been updated anyways.

[tbenr]

LGTM