Updated test to account for flakiness.

[jmkulwik]

We've been hitting an issue in our testing system where the sprites are sometimes doubled. This does not repro on test or production, and it appears to be an issue with either and outdated version of browsers in our testing system or with the web driver that's being used. We suspect that updating the versions will address the issue. In the meantime, to unblock the pipeline, we are ok accepting any number of sprites that is at least 10. That way we can be sure sprites have been generated and also not block on this intermittent (but frequent) issue.

Slack details where this was reported: https://codedotorg.slack.com/archives/C0T0PNTM3/p1699578533080019

Image of doubled sprites

Follow-up task: https://codedotorg.atlassian.net/browse/LABS-241

This is a follow-up from #54876

Links

Testing story

Deployment strategy

Follow-up work

Privacy

Security

Caching

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[breville]

This seems reasonable for a temporary fix, so long as we know it's not a real bug.

It might be worth a comment just above the changed line, maybe using the # TODO: format.