Fix error messages match issue after experiment

Author: miatttao

src/sonic-yang-models/tests/yang_model_tests/tests/vnet_route_tunnel_vxlan.json

@@ -38,7 +38,7 @@
 
     "VNET_ROUTE_TUNNEL_TEST_INVALID_PREFIX": {
         "desc": "VNET route tunnel configuration with invalid prefix format in name field.",
-        "eStr": "Value \"Vnet1\" does not satisfy the constraint"
+        "eStr": "Value \"Vnet1\" does not satisfy the constraint \"[^:]+:((([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])/(([0-9])|([1-2][0-9])|(3[0-2])))\" (range, length, or pattern)"
     },
 
     "VNET_ROUTE_TUNNEL_TEST_MISSING_ENDPOINT": {