test: Add validation on Spark SQL test classes and fix package structure

[yihua]

Describe the issue this Pull Request addresses

Some Spark SQL tests are not executed in CI.

Summary and Changelog

This PR enforces proper package structure for Spark SQL test classes under org.apache.spark.sql.hudi by:

• Adds org.apache.spark.sql.hudi.catalog to the allowed wildcard test suites in CI configuration
• Moves misplaced test classes from org.apache.spark.sql.hudi to org.apache.spark.sql.hudi.common
• Fixes package declarations and imports in affected test files
• Adds TestSparkSqlHudiPackageStructure which validates that Scala test classes under org.apache.spark.sql.hudi are only in allowed packages.

Impact

Fixes test coverage and adds validation to guarantee test coverage in the future.

Risk Level

none

Documentation Update

N/A

Contributor's checklist

• Read through contributor's guide
• Enough context is provided in the sections above
• Adequate tests were added if applicable

[voonhous]

Added some nit comments.

[voonhous]

Comments addressed, LGTM.

Docs will be updated separately.

[hudi-bot]

CI report:

• 6b75fe9 Azure: SUCCESS

Bot commands

@hudi-bot supports the following commands:

• @hudi-bot run azure re-run the last Azure build