Remove variable substituion to %NUM% to correctly invoke local command

Referencing %NUM% must be a mistake, because with it networks are not
deleted properly. See other commands within quantum-adv-test.sh as
an example.

Fixes bug #1164018

Change-Id: Ib222d82a1b8187167606b2543bb74c28b8465b5a
diff --git a/exercises/quantum-adv-test.sh b/exercises/quantum-adv-test.sh
index a1fb2ad..fbb1b77 100755
--- a/exercises/quantum-adv-test.sh
+++ b/exercises/quantum-adv-test.sh
@@ -330,7 +330,7 @@
 }
 
 function delete_networks {
-   foreach_tenant_net 'delete_network ${%TENANT%_NAME} ${%NUM%}'
+   foreach_tenant_net 'delete_network ${%TENANT%_NAME} %NUM%'
    #TODO(nati) add secuirty group check after it is implemented
    # source $TOP_DIR/openrc demo1 demo1
    # nova secgroup-delete-rule default icmp -1 -1 0.0.0.0/0