Add tests for PR #14133 (view with multi unions)

[jonahgao]

We need to add some tests for PR #14133

Hi @Curricane -- thank you for the fix 🙏

Can you please add some tests, ideally in sqllogicteset format to ensure this behavior is not broken in the future.

Here are the instructions: https://github.com/apache/datafusion/tree/main/datafusion/sqllogictest

Ideally you should be able to extend one of the existing test files in https://github.com/apache/datafusion/tree/main/datafusion/sqllogictest/test_files

Perhaps https://github.com/apache/datafusion/blob/main/datafusion/sqllogictest/test_files/ddl.slt

[alamb]

Thank you @Curricane for offering to work on this