test(api): add e2e for auth utils fix for handling null values in group auth rule

[sundersc]

Description of changes

Add E2E tests to verify auth utils fix for handling null values in group claim.

When a model contains an owner rule and groups rule, auth utils were wrongly throwing unauthorized error when groups field is null but owner value is valid. AppSync recently fixes this issue in the service.

This PR adds E2E test to API repo to confirm that fix.

CDK / CloudFormation Parameters Changed

NA

Issue #, if available

NA

Description of how you validated changes

• E2E tests

Checklist

• [x] PR description included
• [x] yarn test passes
• [x] Tests are changed or added
• [ ] Relevant documentation is changed or added (and PR referenced)
• [ ] New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• [ ] Any CDK or CloudFormation parameter changes are called out explicitly

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.