Migrations: Update notebook to omit Mongo credentials from commands when authentication is disabled

[eecavanna]

Description

In this branch, I updated the latest migration notebook so that it (a) automatically omits authentication-related CLI options from Mongo CLI commands when no such authentication information is configured in the notebook's environment; and (b) it prints a "." to the console (as a "sign of life/activity/heartbeat") whenever it validates an additional 10% of the documents in a given collection.

Fixes #672 and #719

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration, if it is not simply make up-test && make test-run.

• I ran the unit tests that target the help function involved
  shell $ python -m unittest -v demo/metadata_migration/notebooks/test_helpers.py

Definition of Done (DoD) Checklist:

• My code follows the style guidelines of this project (have you run black nmdc_runtime/?)
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (in docs/ and in https://github.com/microbiomedata/NMDC_documentation/?)
• I have added tests that prove my fix is effective or that my feature works, incl. considering downstream usage (e.g. https://github.com/microbiomedata/notebook_hackathons) if applicable.
• New and existing unit and functional tests pass locally with my changes (make up-test && make test-run)