cleanup/refactor: Implement and refactor e2e tests for 'alpha generat…

…e' command

- Added comprehensive end-to-end tests for the 'generate' command, ensuring proper validation of the 'PROJECT' file after project initialization and regeneration.
- Verified correct handling of multigroup layouts, Grafana, and DeployImage plugins.
- Refactored test structure to align with established patterns from other tests, improving maintainability and consistency.
- Increased test coverage to support future growth and cover more scenarios.