fix(p2p|sync): Only log head verification failure as error if it is not ErrKnownHeader

[walldiss]

Known headers are not failing verification. They just ignored because we don't need them and thus can be reported as soft failure.

[Wondertan]

Making known headers a soft failure means we will use them as sync target which is wrong.
The issue here is not with the buggy logic but with the logging that confuses node operators, so the solution should be on the logging level, like demoting this error to WARN

[walldiss]

Do you think we need this log as WARN or it should be DEBUG? Does this case need attention from node operator?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6afe95f) 63.77% compared to head (d2c7a7b) 63.79%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #138      +/-   ##
==========================================
+ Coverage   63.77%   63.79%   +0.01%     
==========================================
  Files          39       39              
  Lines        3382     3389       +7     
==========================================
+ Hits         2157     2162       +5     
- Misses       1059     1061       +2     
  Partials      166      166              

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[renaynay]

Note that this PR suppresses a symptom of a problem (likely with recencyThreshold) that the node eagerly requests Head even though one should soon arrive via header-sub

Fixed now

[Wondertan]

Note that this PR suppresses a symptom of a problem (likely with recencyThreshold) that the node eagerly requests Head even though one should soon arrive via header-sub

Please make sure we have a descriptive issue for it and so we don't forget after vanishing it from logs.