remove id field from CDM

There are 3 related fields(id, uuid and hostname) in ComputeNode[1].
according to [2], after nova api 2.53, the id of the hypervisor as a UUID.
and service.host is equal to hypervisor name for compute node.
so we can remove id and only keep uuid then set uuid to node.id

[1]:https://github.com/openstack/watcher/blob/master/watcher/decision_engine/model/collector/nova.py#L306
[2]:https://developer.openstack.org/api-ref/compute/?expanded=list-hypervisors-details-detail#list-hypervisors-details

Change-Id: Ie1d1ad56808270d936ec25186061f7f12cc49fdc
Closes-Bug: #1835192
Depends-on: I752fbfa560313e28e87d83e46431c283b4db4f23
Depends-on: I0975500f359de92b6d6fdea2e01614cf0ba73f05

watcher/tests/decision_engine/cluster/test_nova_cdmc.py

@@ -78,7 +78,7 @@ class TestNovaClusterDataModelCollector(base.TestCase):
             disabled_reason='',
         )
         minimal_node = dict(
-            id=1337,
+            id='160a0e7b-8b0b-4854-8257-9c71dff4efcc',
             hypervisor_hostname='test_hostname',
             state='TEST_STATE',
             status='TEST_STATUS',
@@ -149,7 +149,7 @@ class TestNovaClusterDataModelCollector(base.TestCase):
         node = list(compute_nodes.values())[0]
         instance = list(instances.values())[0]
 
-        self.assertEqual(node.uuid, 'test_hostname')
+        self.assertEqual(node.uuid, '160a0e7b-8b0b-4854-8257-9c71dff4efcc')
         self.assertEqual(instance.uuid, 'ef500f7e-dac8-470f-960c-169486fce71b')
 
         memory_total = node.memory - node.memory_mb_reserved