8189 appointments index schema corrections

[kpethtel]

Summary

Makes corrections to expected schema and prevents running the checks on empty data.

Related issue(s)

department-of-veterans-affairs/va-mobile-app#8189

Testing done

• specs.

Screenshots

Note: Optional

What areas of the site does it impact?

Could impact appointments index but shouldn't impact anything.

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• Events are being sent to the appropriate logging solution
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Feature/bug has a monitor built into Datadog or Grafana (if applicable)
• If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• I added a screenshot of the developed feature

Requested Feedback

[kpethtel]

Adding this guard because only 2 of the first 25 runs had actual data in them. 17 were just empty and 6 had upstream failures (so the data was also empty).