Use MongoDB as a single node replica set

We need Mongo working as a RS because of the change streams functionality which we use for policy synchronization.

@valerii.kalashnikov

env/policy.env

@@ -9,7 +9,7 @@ REDIS_USER=""
 REDIS_PASS=""
 REDIS_DB=1
 REDIS_EXPIRATION="1h"
-MONGO_ADDR="mongodb://mongo:27017/policy?authSource=admin"
+MONGO_ADDR="mongodb://mongo:27017/policy?replicaSet=rs0&authSource=admin"
 MONGO_USER="root"
 MONGO_PASS="root"
 MONGO_DBNAME="policy"