feat(sync-v2): Improve sync-v2 reliability

[msbrogli]

Motivation

The previous organization of responsibilities within sync-v2's internal methods was ambiguous. This Pull Request enhances the clarity by:

1. Distinctly delineating each method's responsibilities.
2. Standardizing the point at which we determine if blocks are synchronized.
3. Designating a consistent time to ask the peer to transmit vertices in real-time.

This refactoring aims to streamline the process, reduce potential errors, and make the codebase more maintainable.

Acceptance Criteria

1. Change find_best_common_block() to just find the best common block. So it will not set sync state and update relay anymore.
2. Simplify logic to decide whether we have something to sync or not.
3. Move the logic to set sync state and to enable/disable real-time relay to the run_sync_blocks() method.

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (c47f06e) 85.01% compared to head (67d5ce4) 85.04%.
Report is 1 commits behind head on master.

❗ Current head 67d5ce4 differs from pull request most recent head 98121c4. Consider uploading reports for the commit 98121c4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #843      +/-   ##
==========================================
+ Coverage   85.01%   85.04%   +0.02%     
==========================================
  Files         271      271              
  Lines       22368    22368              
  Branches     3420     3418       -2     
==========================================
+ Hits        19017    19022       +5     
+ Misses       2675     2671       -4     
+ Partials      676      675       -1     

Files	Coverage Δ
hathor/p2p/sync_v2/agent.py	75.64% <92.59%> (+0.43%)	⬆️

... and 1 file with indirect coverage changes

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The base branch was changed.