style(gservice): extract machine_pool_agent's uuid to a named variable

Match the surrounding file's own convention (e.g. the set_agent block
right below) instead of inlining the uuid5 call as a constructor arg.

Author: VasilyStepanov

exordos_core/gservice/service.py

@@ -106,14 +106,16 @@ def __init__(self, iter_min_period=3, iter_pause=0.1):
         pool_driver = ua_pool_drivers.PoolAgentDriver(
             meta_file="/var/lib/exordos/exordos_core/pool_agent_meta.json"
         )
+        agent_uuid = sys_uuid.uuid5(ua_utils.system_uuid(), "machine_pool_agent")
         machine_pool_agent = ua_agent_service.UniversalAgentService(
-            agent_uuid=sys_uuid.uuid5(ua_utils.system_uuid(), "machine_pool_agent"),
+            agent_uuid=agent_uuid,
             orch_client=orch_db.DatabaseOrchClient(),
             caps_drivers=[pool_driver],
             facts_drivers=[],
             iter_min_period=iter_min_period,
             payload_path=None,
         )
+
         set_builder = set_builder_svc.NodeSetBuilderService(
             instance_model=node_set_models.NodeSet,
             project_id=nc.NODE_SET_PROJECT,