Suppress metrics table in passing test runs

[andyleiserson]

std::io::stdout() is not captured in test runs -- see rust-lang/rust#90785.

The Display implementation for comfy_table::Table assembles everything into a string anyways (actually worse -- it assembles into a Vec<String> and then calls join). So, even if we were to have other places where we want the std::io::Write interface, there is unlikely to be a performance benefit of the previous implementation.

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 93.54%. Comparing base (95dbe6a) to head (04ce112).
Report is 17 commits behind head on main.

Files with missing lines	Patch %	Lines
ipa-core/src/telemetry/stats.rs	95.23%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1400      +/-   ##
==========================================
- Coverage   93.68%   93.54%   -0.15%     
==========================================
  Files         223      223              
  Lines       37765    38261     +496     
==========================================
+ Hits        35382    35792     +410     
- Misses       2383     2469      +86     

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[akoshelev]

oh, that was my bad, thanks for fixing it!