Revert pipenv activation to not use pipenv shell

[karrtikr]

For #4394

• 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!)
• Has sufficient logging.
• Has telemetry for enhancements.
• Unit tests & system/integration tests are added/updated
• Test plan is updated as appropriate
• package-lock.json has been regenerated by running npm install (if dependencies have changed)

[codecov]

Codecov Report

Merging #4406 into master will increase coverage by 21%.
The diff coverage is 50%.

@@           Coverage Diff            @@
##           master   #4406     +/-   ##
========================================
+ Coverage      57%     78%    +21%     
========================================
  Files         364     439     +75     
  Lines       15495   20522   +5027     
  Branches     2408    3290    +882     
========================================
+ Hits         8752   15810   +7058     
+ Misses       6163    4708   -1455     
+ Partials      580       4    -576

Flag	Coverage Δ
#Linux	66% <50%> (?)
#Windows	66% <50%> (?)
#macOS	66% <50%> (?)

[DonJayamanne]

Please fix compilation issues (see Azdo CI errors)

[DonJayamanne]

Please fix CI issues

done