HIGH-007: V2 block callbacks can block consensus message pipeline before admissibility checks

[sstanculeanu]

Reasoning behind the pull request

• realized that the wait method is not needed, this is already handled on worker
• also, the header received earlier was called from pool, thus it is safe to early exit if start round not finished

Proposed changes

• removed the recently added method

Testing procedure

• with feat branch

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?