Remove unnecessary test in user sessions test

[satokaito]

Changes

I noticed that an unnecessary user_authentication_method test was being executed in user_sessions tests, so I removed it.

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• [ ] This change adds unit test coverage
• [ ] This change adds integration test coverage
• [x] This change has been tested on the latest version of Ruby

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All existing and new tests complete without errors
• [x] Rubocop passes on all added/modified files
• [x] All active GitHub checks have passed