This commit updates the `Scheduler` to support cooperative shutdown using `Notify`, allowing graceful termination of tasks and cleanup of placeholder VMs. Additionally, the AMQP consumer is enhanced with an explicit shutdown mechanism, ensuring proper resource cleanup, including closing channels and connections.
This commit introduces the ability to configure placeholder VM run time via an environment variable (`VM_PLACEHOLDER_RUN_SECS`) and updates the `Scheduler` to accept this duration. Additionally, it implements a graceful shutdown mechanism for the orchestrator, allowing cooperative shutdown of consumers and cleanup of resources.
