params(share/shwap/p2p/shrex/shrexnd): Increase concurrency limit for shrexnd middleware

[renaynay]

I changed it specifically for shrexnd server (which is a bit ugly) but I don't want to increase shrex-eds server limit even though we deprecated FNs because users are likely still running FNs and I don't want them to bombard BNs.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 35.83%. Comparing base (2469e7a) to head (9a9bfd4). Report is 501 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4286      +/-   ##
==========================================
- Coverage   44.83%   35.83%   -9.01%     
==========================================
  Files         265      312      +47     
  Lines       14620    22974    +8354     
==========================================
+ Hits         6555     8232    +1677     
- Misses       7313    13875    +6562     
- Partials      752      867     +115     

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