Remove each subdir once tar'd for backup

[imnasnainaec]

Ameliorates #3944, dropping storage usage (approximately) from 14 GB to 12 GB.

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This change is 

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.08%. Comparing base (1d486be) to head (6bf4bd2).
⚠️ Report is 49 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3947   +/-   ##
=======================================
  Coverage   74.08%   74.08%           
=======================================
  Files         292      292           
  Lines       10653    10653           
  Branches     1347     1347           
=======================================
  Hits         7892     7892           
  Misses       2376     2376           
  Partials      385      385           

Flag	Coverage Δ
backend	85.29% <ø> (ø)
frontend	65.67% <ø> (ø)

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[jasonleenaylor]

@jasonleenaylor reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @imnasnainaec)