[SDK] Restore configured MaxScale after delta histogram collection

[matt-hensley]

Changes

Restores configured MaxScale after a delta exponential-histogram is collected.

MaxScale is the maximum scale available to an exponential histogram stream, so resetting or copying the histogram should not discard that configuration, per the metrics SDK spec.

This restores the config after collection and when copying a histogram, while preserving the reset behavior introduced in #6557.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

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Pull request dashboard status

Merged · refreshed 2026-08-21 08:47 UTC

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.38%. Comparing base (f6f6022) to head (7d5d9b3).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7671      +/-   ##
==========================================
- Coverage   91.39%   91.38%   -0.02%     
==========================================
  Files         318      318              
  Lines       17810    17812       +2     
==========================================
  Hits        16278    16278              
- Misses       1532     1534       +2     

Flag	Coverage Δ
unittests-Project-Experimental	91.45% <100.00%> (-0.03%)	⬇️
unittests-Project-Stable	91.47% <100.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ics/MetricPoint/Base2ExponentialBucketHistogram.cs	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes