should proposer boost be counted in `is_parent_strong`?

[potuz]

In Gloas we change is_parent_strong to only count the attestation score and no longer proposer boost. In previous forks we use get_weight which also counts proposer boost for it.

Most of the applications for is_parent_strong are done at the beginning of the slot when the proposer is about to choose head to propose, so anyway there won't be a proposer boost root set, but should_override_forkchoice_update may cause trouble cause implementers may count attestations early without running new_slot and without unsetting proposer boost root, this would lead to different behaviors pre and post-gloas.