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/decision_engine/datasources/ceilometer.py

@@ -175,7 +175,7 @@ class CeilometerHelper(base.DataSourceBase):
 
         resource_id = resource.uuid
         if resource_type == 'compute_node':
-            resource_id = "%s_%s" % (resource.uuid, resource.hostname)
+            resource_id = "%s_%s" % (resource.hostname, resource.hostname)
 
         query = self.build_query(
             resource_id=resource_id, start_time=start_time, end_time=end_time)

watcher/decision_engine/datasources/gnocchi.py

@@ -84,7 +84,7 @@ class GnocchiHelper(base.DataSourceBase):
 
         resource_id = resource.uuid
         if resource_type == 'compute_node':
-            resource_id = "%s_%s" % (resource.uuid, resource.hostname)
+            resource_id = "%s_%s" % (resource.hostname, resource.hostname)
             kwargs = dict(query={"=": {"original_resource_id": resource_id}},
                           limit=1)
             resources = self.query_retry(