Stop the guest api if a VM fail to start

Author: olethanh

src/aleph/vm/models.py

@@ -334,6 +334,7 @@ async def start(self):
             await self.save()
         except Exception:
             await self.vm.teardown()
+            await self.vm.stop_guest_api()
             raise
 
     async def wait_for_init(self):