refactor(otlp-exporter-base): remove unnecessary isNaN() checks

[cjihrig]

Which problem is this PR solving?

This PR removes validation code that is not needed.

Fixes N/A

Short description of the changes

This commit removes two Number.isNaN() checks. These checks are not needed because the Number.isFinite() checks they are paired with also detect NaN values.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Ran the existing test suite which includes NaN tests for one of the checks.
• Added unit tests for the other NaN check that did not appear to be tested.

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.54%. Comparing base (f927e82) to head (8167313).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5374      +/-   ##
==========================================
- Coverage   94.54%   94.54%   -0.01%     
==========================================
  Files         318      318              
  Lines        8052     8046       -6     
  Branches     1694     1688       -6     
==========================================
- Hits         7613     7607       -6     
  Misses        439      439              

Files with missing lines	Coverage Δ
...ter-base/src/configuration/shared-configuration.ts	100.00% <100.00%> (ø)
...base/src/configuration/shared-env-configuration.ts	100.00% <100.00%> (ø)

[pichlermarc]

thanks 👍