[OWL-1105][query] refine func getExistedHosts()
[OWL-1105][query] refine func getExistedHosts()

Cepave/open-falcon-backend,masato25/open-falcon-backend,Cepave/open-falcon-backend,masato25/open-falcon-backend,Cepave/open-falcon-backend,masato25/open-falcon-backend,Cepave/open-falcon-backend,masato25/open-falcon-backend,masato25/open-falcon-backend,Cepave/open-falcon-backend,Cepave/open-falcon-backend,masato25/open-falcon-backend