chore: changing all test public api to internal

[fluong6]

Migrating all the access modifiers from Public to Internal for test classes.

Changelog

• Added: The package whose Changelog should be added to should be in the header. Delete the changelog section entirely if it's not needed.
• Fixed: If you update multiple packages, create a new section with a new header for the other package.
• Removed/Deprecated/Changed: Each bullet should be prefixed with Added, Fixed, Removed, Deprecated, or Changed to indicate where the entry should go.

Testing and Documentation

• No tests have been added.