Make randomize default to true in the frontend

[rtibbles]

Summary

Description of the change(s) you made

• If randomize is undefined on an Exercise ContentNode's extra_fields, the publishing task defaults to set it to true
• In the frontend if it is undefined, it shows it as unchecked in the interface
• This brings the frontend inline with the backend

Manual verification steps performed

1. Create a new exercise
2. Observe that the Randomize question order for learners checkbox is checked
3. Go into the IndexedDB contentnode table and search for the id of this new exercise
4. Observe that extra_fields is still an empty object

Screenshots (if applicable)

References

Fixes #3244

Comments

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Contributor's Checklist

PR process:

• If this is an important user-facing change, PR or related issue the CHANGELOG label been added to this PR. Note: items with this label will be added to the CHANGELOG at a later time
• If this includes an internal dependency change, a link to the diff is provided
• The docs label has been added if this introduces a change that needs to be updated in the user docs?
• If any Python requirements have changed, the updated requirements.txt files also included in this PR
• Opportunities for using Google Analytics here are noted
• Migrations are safe for a large db

Studio-specifc:

• All user-facing strings are translated properly
• The notranslate class been added to elements that shouldn't be translated by Google Chrome's automatic translation feature (e.g. icons, user-generated text)
• All UI components are LTR and RTL compliant
• Views are organized into pages, components, and layouts directories as described in the docs
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Testing:

• Code is clean and well-commented
• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Any new interactions have been added to the QA Sheet
• Critical and brittle code paths are covered by unit tests

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Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

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[bjester]

Verified randomize field in channel export database