refactor: Clean up AssetManagerTest by removing redundant tests and c…

…onsolidating configurations

- Removed several test cases that were redundant or overly complex, focusing on essential scenarios for AssetManager's behavior.
- Consolidated Git configuration tests into static final strings for better readability and maintainability.
- Streamlined the setup process for tests, ensuring clarity in the initialization of AssetManager instances.
- Enhanced the clarity of the remaining tests by improving comments and structure, making it easier to understand the purpose of each test case.