Revert "Revert "Fix deadlock when deleting a host with running VMs""

This reverts commit ef260045a15eab39da321d7e46f9c0a5f1fa0d42.
Revert "Revert "StopMonitor action for IM dummy drivers""

This reverts commit 3a67b4e4c88416196e36976440e61c824dfdb562.