Enable the message box on default for satelitte announcement actions (#141654)

homeassistant/components/assist_satellite/services.yaml

@@ -8,6 +8,7 @@ announce:
     message:
       required: false
       example: "Time to wake up!"
+      default: ""
       selector:
         text:
     media_id:
@@ -28,6 +29,7 @@ start_conversation:
     start_message:
       required: false
       example: "You left the lights on in the living room. Turn them off?"
+      default: ""
       selector:
         text:
     start_media_id: