Renamed `DatabaseConfiguration` to `DbConnectionConfig` for clarity. Replaced `.toDF` with `.readDataFrame` methods to improve method naming consistency. These changes enhance code readability and maintainability.

Simplify the logic to use single-expression functions for readability. Ensure consistent formatting and make error messages more explicit. This change also corrects minor indentation issues in SQL query strings within tests.

This commit updates various imports and references from DatabaseConfiguration to DbConnectionConfig across different files. This change ensures consistency in the naming convention used throughout the codebase and documentation, improving clarity and maintenance.