Add dummy migration for migration rollback testing

[zubair-arbi]

Jira Ticket: EDLY-1708
Related Ticket: EDLY-911

This branch was create to create a dummy migration which can be used by the devops to test release rollback including the migrations.

Testing Instructions:

1. Create a new dummy release tag for testing this change on stage multisites edly-test-1.1.0
2. Devops will deploy this release tag
3. Verify that changes are on stage (the dummy_field in EdlyUserProfile model)
4. Devops will rollback this release by reverting to previous stable release tag edly-2.3.0 (https://github.com/edly-io/edx-platform/releases/tag/edly-2.3.0)
5. Verify that ansible playbook for rollback is successfully commpleted without any error
6. Verify that the changes are stage (the dummy_field in EdlyUserProfile model) were reverted

Note: Don't merge this PR. Its created for testing purpose only.

[zubair-arbi]

@ziafazal @NIXKnight @jamshedali20 I have created this PR with a test migration for release rollback testing.

I have also create the test release https://github.com/edly-io/edx-platform/releases/tag/edly-test-1.0.0 against it.

[NIXKnight]

This PR has been open since October 2020 and the description explicitly states "Don't merge this PR". It was created for migration rollback testing.

If the testing has been completed, this PR should be closed. If the testing is still needed, consider:

1. The migration (line 18) uses a bytes literal help_text=b'...' which was auto-generated by Django 1.11 for Python 2 compatibility. On Python 3 this will cause issues since help_text expects a string, not bytes.
2. The model definition in models.py correctly uses a regular string help_text='...', so only the migration file has the mismatch.

Recommendation: close this PR.

[NIXKnight]

See comment for details. This 5-year-old PR should be closed.

[jamshedali20]

@muhammadali286 could you please look into it?