fix(rust): Ensure eprintln! is only called within debug/verbose context

[mcrumiller]

Resolves #15099.

Also found one more eprintln that wasn't properly wrapped.

Not worth adding a unit test, but OP's example no longer prints the result to stderr.

[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 81.06%. Comparing base (be92470) to head (311bd66).

Files	Patch %	Lines
...rc/physical_plan/executors/group_by_partitioned.rs	33.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15100      +/-   ##
==========================================
- Coverage   81.07%   81.06%   -0.02%     
==========================================
  Files        1342     1342              
  Lines      173942   173948       +6     
  Branches     2459     2459              
==========================================
- Hits       141021   141008      -13     
- Misses      32455    32474      +19     
  Partials      466      466              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ritchie46]

Thank you @mcrumiller!