ID of multiple notifications based on a single event differs from each other

[Masaki UENO]

According to SOL003 v3.3.1, ID of VnfLcmOperationOccurrenceNotification is defined as below:

"Identifier of this notification. If a notification is sent multiple times due to multiple subscriptions, the "id" attribute of all these notifications shall have the same value."

However, Tacker Antelope implementation generates multiple notification on a single event with differrent IDs[1].

[1] https://github.com/openstack/tacker/blob/40a15b59455fdc6b34eecd641af514d32888a5a2/tacker/sol_refactored/nfvo/nfvo_client.py#L207-L212

```
    def send_lcmocc_notification(self, context, lcmocc, inst, endpoint):
        subscs = subsc_utils.get_lcmocc_subscs(context, lcmocc, inst)
        for subsc in subscs:
            notif_data = lcmocc_utils.make_lcmocc_notif_data(
                subsc, lcmocc, endpoint)
            common_script_utils.send_notification(subsc, notif_data)

        if self.is_local:
            self.nfvo.recv_lcmocc_notification(context, lcmocc, inst)
```

`send_lcmocc_notification` method is called when a LCM event (including state transition) occurs, thus ID of notification should be generated at the top of this method. However, ID of notification is generated by `make_lcmocc_notif_data` method, which is called at each step of for-loop.

I think we can resolve this issue by:

1. Generate UUID outside of for-loop
2. Use UUID generated at step 1 as argument of `make_lcmocc_notif_data` method