Restrict existing strategies to their default scope

Diffrent stratege has diffrent default scope, restrict them to their
default scope will avoid usage problems.
1)workload_balancing/thermal_optimization/airflow_optimization goals
  react on enabled nodes, so restrict default scope to compute nodes
  with up state and enabled status.
2)server_consolidation goal react on enabled or disabled nodes, So
  restrict default scope to compute nodes with up state and
  enabled/disabled status.

Change-Id: I7437dee699ee2d3dd227a047196d4d8db811b81e
Closes-Bug: #1714002

watcher/decision_engine/strategy/strategies/outlet_temp_control.py

@@ -171,6 +171,13 @@ class OutletTempControl(base.ThermalOptimizationBaseStrategy):
                 choices=["ceilometer", "gnocchi"])
         ]
 
+    def get_available_compute_nodes(self):
+        default_node_scope = [element.ServiceState.ENABLED.value]
+        return {uuid: cn for uuid, cn in
+                self.compute_model.get_all_compute_nodes().items()
+                if cn.state == element.ServiceState.ONLINE.value and
+                cn.status in default_node_scope}
+
     def calc_used_resource(self, node):
         """Calculate the used vcpus, memory and disk based on VM flavors"""
         instances = self.compute_model.get_node_instances(node)
@@ -186,7 +193,7 @@ class OutletTempControl(base.ThermalOptimizationBaseStrategy):
 
     def group_hosts_by_outlet_temp(self):
         """Group hosts based on outlet temp meters"""
-        nodes = self.compute_model.get_all_compute_nodes()
+        nodes = self.get_available_compute_nodes()
         size_cluster = len(nodes)
         if size_cluster == 0:
             raise wexc.ClusterEmpty()