Fix failing functional extension tests in CI related to pytest discovery.

[ericsnowcurrently]

(for #6940)

This is essentially a follow-up to #6877 (for #6758).

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• Title summarizes what is changing
• Has a news entry file (remember to thank yourself!)
• [ ] Appropriate comments and documentation strings in the code
• [ ] Has sufficient logging.
• [ ] Has telemetry for enhancements.
• Unit tests & system/integration tests are added/updated
• [ ] Test plan is updated as appropriate
• [ ] package-lock.json has been regenerated by running npm install (if dependencies have changed)
• [ ] The wiki is updated with any design decisions/details.