Ensure file paths are not sent in telemetry when running unit tests

[DonJayamanne]

Fixes #1180

This pull request:

• Has a title summarizes what is changing
• Includes a news entry file (remember to thank yourself!)
• Has unit tests & code coverage is not adversely affected (within reason)
• Works on all actively maintained versions of Python (e.g. Python 2.7 & the latest Python 3 release)
• Works on Windows 10, macOS, and Linux (e.g. considered file system case-sensitivity)

[codecov]

Codecov Report

Merging #1197 into master will decrease coverage by 0.11%.
The diff coverage is 78.26%.

@@            Coverage Diff             @@
##           master    #1197      +/-   ##
==========================================
- Coverage   71.95%   71.84%   -0.12%     
==========================================
  Files         260      260              
  Lines       11922    11919       -3     
  Branches     2116     2116              
==========================================
- Hits         8579     8563      -16     
- Misses       3219     3226       +7     
- Partials      124      130       +6

Impacted Files	Coverage Δ
src/client/unittests/codeLenses/testFiles.ts	18.64% <100%> (ø)	⬆️
src/client/unittests/main.ts	50.75% <100%> (ø)	⬆️
src/client/unittests/display/picker.ts	21.33% <25%> (-0.53%)	⬇️
src/client/unittests/common/testUtils.ts	68.47% <66.66%> (-0.68%)	⬇️
src/client/debugger/PythonProcess.ts	45.41% <0%> (-3.34%)	⬇️
...rc/client/debugger/PythonProcessCallbackHandler.ts	51.64% <0%> (-1.32%)	⬇️
src/client/linters/lintingEngine.ts	90.35% <0%> (-0.88%)	⬇️

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