Exponential Bucket Histogram - part 6

[reyang]

Following #3462.

Changes

• Minor clean up.
• Test improvements (which is important for testing positive scales).

[codecov]

Codecov Report

Merging #3494 (88fb9cd) into main (6f2b1a0) will not change coverage.
The diff coverage is 50.00%.

@@           Coverage Diff           @@
##             main    #3494   +/-   ##
=======================================
  Coverage   86.32%   86.32%           
=======================================
  Files         270      270           
  Lines        9865     9865           
=======================================
  Hits         8516     8516           
  Misses       1349     1349           

Impacted Files	Coverage Δ
src/OpenTelemetry/Internal/MathHelper.cs	90.47% <ø> (+6.03%)	⬆️
...penTelemetry/Metrics/ExponentialBucketHistogram.cs	41.17% <50.00%> (-4.66%)	⬇️
src/OpenTelemetry/Logs/OpenTelemetryLogger.cs	86.66% <0.00%> (-2.23%)	⬇️
...heus/Implementation/PrometheusCollectionManager.cs	82.27% <0.00%> (+2.53%)	⬆️