[OldMongo FC-0004] Tests for removing support for children in Old Mongo - part 2

[UvgenGen]

Description

Should be merged after first part: #31422
Second part of preparing tests for Remove support for children in Old Mongo task (#31134).

• Fixed problem with .get_children() in tests for split modulestore.
  Problem: If we create some CourseItem with some parent, we must get the updated parent item before using that parent item.
• Updated CourseOverview Signals Tests for split modulestore. (problem with timezone for datetime field, get_children, )
• Updated test_assets.py for split modulestore. (assets paths/urls)

Useful information to include:
First part: #31422
Remove support for children in Old Mongo PR: #31134
openedx/public-engineering#80

[openedx-webhooks]

Thanks for the pull request, @UvgenGen! Please note that it may take us up to several weeks or months to complete a review and merge your PR.

Feel free to add as much of the following information to the ticket as you can:

• supporting documentation
• Open edX discussion forum threads
• timeline information ("this must be merged by XX date", and why that is)
• partner information ("this is a course on edx.org")
• any other information that can help Product understand the context for the PR

All technical communication about the code itself will be done via the GitHub pull request interface. As a reminder, our process documentation is here.

Please let us know once your PR is ready for our review and all tests are green.

[mphilbrick211]

Hi @UvgenGen - is this ready for review?

[UvgenGen]

Hi @mphilbrick211. Yes, it's ready for review

[mphilbrick211]

Flagging this for you @ormsbee!

[ormsbee]

I'll merge this later today

[openedx-webhooks]

@UvgenGen 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the staging environment in preparation for a release to production.

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the production environment.