Do not set foreground colors of test status bar

[DonJayamanne]

For #4387

Not adding tests as this PR removes code.

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• Title summarizes what is changing
• Has a news entry file (remember to thank yourself!)
• [n/a] Appropriate comments and documentation strings in the code
• [n/a] Has sufficient logging.
• [n/a] Has telemetry for enhancements.
• [n/a] Unit tests & system/integration tests are added/updated
• [n/a] Test plan is updated as appropriate
• [n/a] package-lock.json has been regenerated by running npm install (if dependencies have changed)
• [n/a] The wiki is updated with any design decisions/details.

[codecov-io]

Codecov Report

Merging #7651 into master will decrease coverage by 0.33%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7651      +/-   ##
==========================================
- Coverage   58.68%   58.35%   -0.34%     
==========================================
  Files         493      493              
  Lines       21997    21990       -7     
  Branches     3533     3528       -5     
==========================================
- Hits        12909    12832      -77     
- Misses       8279     8349      +70     
  Partials      809      809

Impacted Files	Coverage Δ
src/client/testing/display/main.ts	82.5% <ø> (+1.39%)	⬆️
src/client/testing/serviceRegistry.ts	48.64% <0%> (-46.85%)	⬇️
src/client/testing/codeLenses/main.ts	44.44% <0%> (-33.34%)	⬇️
...t/datascience/jupyter/jupyterDataRateLimitError.ts	66.66% <0%> (-33.34%)	⬇️
src/client/formatters/serviceRegistry.ts	75% <0%> (-25%)	⬇️
src/client/common/utils/icons.ts	83.33% <0%> (-16.67%)	⬇️
src/client/api.ts	78.57% <0%> (-14.29%)	⬇️
src/client/datascience/cellFactory.ts	75.86% <0%> (-13.8%)	⬇️
src/client/common/utils/platform.ts	76.47% <0%> (-11.77%)	⬇️
src/client/providers/providerUtilities.ts	83.33% <0%> (-5.56%)	⬇️
... and 2 more

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