Move unit testing data to the mlcommons storage

[sarthakpati]

Fixes #721

Proposed Changes

• moving to use mlcommons storage instead of penn box

Checklist

• I have read the CONTRIBUTING guide.
• My PR is based from the current GaNDLF master .
• Non-breaking change (does not break existing functionality): provide as many details as possible for any breaking change.
• Function/class source code documentation added/updated.
• Code has been blacked for style consistency.
• If applicable, version information has been updated in GANDLF/version.py.
• If adding a git submodule, add to list of exceptions for black styling in pyproject.toml file.
• Usage documentation has been updated, if appropriate.
• Tests added or modified to cover the changes; if coverage is reduced, please give explanation.
• If customized dependency installation is required (i.e., a separate pip install step is needed for PR to be functional), please ensure it is reflected in all the files that control the CI, namely: python-test.yml, and all docker files [1,2,3].

[github-actions]

MLCommons CLA bot All contributors have signed the MLCommons CLA ✍️ ✅

[codecov]

Codecov Report

Merging #722 (90af114) into master (b230e02) will increase coverage by 0.00%.
Report is 4 commits behind head on master.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #722   +/-   ##
=======================================
  Coverage   94.69%   94.69%           
=======================================
  Files         117      117           
  Lines        8219     8221    +2     
=======================================
+ Hits         7783     7785    +2     
  Misses        436      436           

Flag	Coverage Δ
unittests	94.69% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
testing/test_full.py	99.15% <100.00%> (+<0.01%)	⬆️

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