core:autopilot_manager: Fix race setting router

* Change to use stop and start since directlly changing the router
  without modifying should_be_running can cause multiple starts

core/services/ardupilot_manager/mavlink_proxy/Manager.py

@@ -124,12 +124,12 @@ async def set_preferred_router(self, router_name: str) -> None:
  try:
  endpoints = self.endpoints()
  master_endpoint = self.master_endpoint
- await self.tool.exit()
+ await self.stop()
  self.tool = AbstractRouter.get_interface(router_name)()
  for endpoint in endpoints:
  self.tool.add_endpoint(endpoint)
  if master_endpoint:
- await self.tool.start(master_endpoint)
+ await self.start(master_endpoint)
  except Exception as error:
  logger.error(f"Failed to set preferred router to {router_name}. {error}")