test(auto-instr-node): show result of setting both env vars

[JamieDanielson]

Which problem is this PR solving?

• More clarity around what happens if both environment variables are set for enabling and disabling instrumentations

Short description of the changes

• Add debug message describing disabled instrumentations if both OTEL_NODE_ENABLED_INSTRUMENTATIONS and OTEL_NODE_DISABLED_INSTRUMENTATIONS environment variables are both set.
• Add test asserting that instrumentation is disabled when both environment variables are set.

Note this test is intended to show current state. If we want to change the behavior so that one wins over the other, that is an option, but is not the purpose of this PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.40%. Comparing base (dfb2dff) to head (1f42b6d).
Report is 193 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2325      +/-   ##
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- Coverage   90.97%   90.40%   -0.57%     
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  Files         146      149       +3     
  Lines        7492     7371     -121     
  Branches     1502     1532      +30     
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- Hits         6816     6664     -152     
- Misses        676      707      +31     

see 63 files with indirect coverage changes