[main] Fix a file-based app package test

[jjonescz]

Fixes #52439.

[Copilot]

Pull request overview

This PR fixes a test failure in the file-based app package test by updating it to use a locally generated test package instead of the external "Humanizer" package. This change makes the test more reliable and self-contained by eliminating the dependency on external package sources.

Changes:

• Replaced the "Humanizer" package reference with a locally generated "A" package
• Added logic to create multiple versions of the test package and configure restore sources
• Updated the Central Package Management version specification to match the test package