Improves block deduplication on batch processing

[farazdagi]

What type of PR is this?

Bug fix

What does this PR do? Why is it needed?

• On valid but forked blocks (in batches), we might get stuck in init-sync. In block-by-block processing this issue has been resolved by checking DB/cache for block's root (and only then deciding that block is duplicate). This PR applies that fix to batch processor as well.

Which issues(s) does this PR fix?

Fixes #6598

Other notes for review

• This PR also fixes test (as we know updated 2nd stage, peers need to have not only finalized, but non-finalized blocks as queue will freely request beyond the finalized epoch). So, updated tests config a bit.

[codecov]

Codecov Report

Merging #7075 into master will decrease coverage by 0.26%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #7075      +/-   ##
==========================================
- Coverage   62.57%   62.30%   -0.27%     
==========================================
  Files         405      403       -2     
  Lines       31760    31485     -275     
==========================================
- Hits        19873    19616     -257     
+ Misses       9120     9090      -30     
- Partials     2767     2779      +12