storage: don't select an SSVM that is removed (#3668)

In case an older SSVM is removed without changing it's state from Up
to Destroyed/Removed etc, the SSVM may be randomly selected for image
store related operations. This fix ensures that endpoints for an image
store are found only from a set of SSVM hosts that are not removed.

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

engine/storage/src/main/java/org/apache/cloudstack/storage/endpoint/DefaultEndPointSelector.java

@@ -263,6 +263,7 @@ public class DefaultEndPointSelector implements EndPointSelector {
         }
         sc.and(sc.entity().getStatus(), Op.IN, Status.Up, Status.Connecting);
         sc.and(sc.entity().getType(), Op.EQ, Host.Type.SecondaryStorageVM);
+        sc.and(sc.entity().getRemoved(), Op.NULL);
         return sc.list();
     }