Fix 70% of rounding performance issue

[thorbjoernl]

Change Summary

Ensures rounding of stats is performed on numpy arrays instead of iterating over a dict, improving performance.

Related issue number

#1277

Checklist

• Start with a draft-PR
• The PR title is a good summary of the changes
• PR is set to AeroTools and a tentative milestone
• Documentation reflects the changes where applicable
• Tests for the changes exist where applicable
• Tests pass locally
• Tests pass on CI
• At least 1 reviewer is selected
• Make PR ready to review

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.04%. Comparing base (01a158a) to head (dc40c69).
Report is 1 commits behind head on main-dev.

Additional details and impacted files

@@            Coverage Diff            @@
##           main-dev    #1278   +/-   ##
=========================================
  Coverage     79.04%   79.04%           
=========================================
  Files           136      136           
  Lines         20786    20786           
=========================================
  Hits          16431    16431           
  Misses         4355     4355           

Flag	Coverage Δ
unittests	79.04% <100.00%> (ø)

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[heikoklein]

Thanks

[lewisblake]

Thing to keep in mind: this approach will not work as intended if the numbers are represented as 32-bit floats. Since they are 64-bit floats, we should be good for now.