v23.08.00: adding unit test for end-to-end example (#669)

* adding unit test for multi-gpu example

* added test for notebook 03

* fixed formatting

* update

* update

* Update 01-ETL-with-NVTabular.ipynb

day of week is between 0 and 6; it must be scaled with a max value of 6 to produce correct values from the 0-1 range. If we do col+1 and scale with 7, then a section of the 0-2pi range (for Sine purposes) will not be represented.

* Update 01-ETL-with-NVTabular.ipynb

Reversed the previous edit for weekday scaling. It is correct that it should be scaled between 0-7, because day 0 (unused/nonapplicable after +1 added) overlaps with day 7 for Sine purposes. Monday should scale to 1/7, Sunday should scale to 7/7 to achieve even distribution of days along the sinus curve.

* reduce num_rows

* Update test_end_to_end_session_based.py

* Update 01-ETL-with-NVTabular.ipynb

* updated test script and notebook

* updated file

* removed nb3 test due to multi-gpu freezing issue

* revised notebooks, added back nb3 test

* fixed test file with black

* update test py

* update test py

* Use `python -m torch.distributed.run` instead of `torchrun`

The `torchrun` script installed in the system is a python script with
a shebang line starting with `#!/usr/bin/python3`

This picks up the wrong version of python when running in a virtualenv
like our tox test environment.

If instead this were `#!/usr/bin/env python3` it would work ok in a
tox environment to call `torchrun`.

However, until either the pytorch package is updated for this to
happen or we update our CI image for this to take place. Running the
python command directly is more reliable.

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Co-authored-by: rnyak <ronayak@hotmail.com>
Co-authored-by: edknv <109497216+edknv@users.noreply.github.com>
Co-authored-by: rnyak <16246900+rnyak@users.noreply.github.com>
Co-authored-by: Oliver Holworthy <1216955+oliverholworthy@users.noreply.github.com>