test(sdk-node): ensure process.env is cleaned up between tests

[cjihrig]

Which problem is this PR solving?

Some of the sdk-node tests currently clean up their modified environment variables at the end of each test. This is unreliable because if a given test fails, the clean up code is not run, and can leak environment variables into surrounding tests.

I believe this is the last file with this problem, so this should conclude the process.env cleanup PRs.

Fixes # N/A

Short description of the changes

This commit updates the appropriate tests to ensure that modified environment variables are cleaned up between tests.

Type of change

Please delete options that are not relevant.

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

How Has This Been Tested?

• Existing test suite

Checklist:

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.16%. Comparing base (c358db1) to head (d52dc0f).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6066   +/-   ##
=======================================
  Coverage   95.16%   95.16%           
=======================================
  Files         316      316           
  Lines        9207     9207           
  Branches     2075     2075           
=======================================
  Hits         8762     8762           
  Misses        445      445           

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[JacksonWeber]

LGTM and thank you for helping improve the test reliability.

[otelbot]

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