Add integration_type service to datadog (home-assistant#158927)

Author: joostlek

homeassistant/components/datadog/manifest.json

@@ -4,6 +4,7 @@
   "codeowners": [],
   "config_flow": true,
   "documentation": "https://www.home-assistant.io/integrations/datadog",
+  "integration_type": "service",
   "iot_class": "local_push",
   "loggers": ["datadog"],
   "quality_scale": "legacy",

homeassistant/generated/integrations.json

@@ -1206,7 +1206,7 @@
     },
     "datadog": {
       "name": "Datadog",
-      "integration_type": "hub",
+      "integration_type": "service",
       "config_flow": true,
       "iot_class": "local_push"
     },