misc(share/shwap/p2p/shrex): add traces to shrex client/server hotpaths

[renaynay]

Overrides #4498

[codecov-commenter]

Codecov Report

❌ Patch coverage is 81.39535% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 35.53%. Comparing base (2469e7a) to head (84c46d6).
⚠️ Report is 578 commits behind head on main.

Files with missing lines	Patch %	Lines
share/shwap/p2p/shrex/client.go	73.33%	4 Missing ⚠️
share/shwap/p2p/shrex/server.go	85.71%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4537      +/-   ##
==========================================
- Coverage   44.83%   35.53%   -9.30%     
==========================================
  Files         265      304      +39     
  Lines       14620    24337    +9717     
==========================================
+ Hits         6555     8649    +2094     
- Misses       7313    14742    +7429     
- Partials      752      946     +194     

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