rbd: make image features as optional parameter

Makes the rbd images features in the storageclass
as optional so that default image features of librbd
can be used. and also kept the option to user
to specify the image features in the storageclass.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

e2e/rbd_helper.go

@@ -149,6 +149,10 @@ func createRBDStorageClass(
 	sc.Parameters["clusterID"] = fsID
 	for k, v := range parameters {
 		sc.Parameters[k] = v
+		// if any values are empty remove it from the map
+		if v == "" {
+			delete(sc.Parameters, k)
+		}
 	}
 	sc.Namespace = cephCSINamespace