Use common strings for Lutron Caseta config flow (#41241)

homeassistant/components/lutron_caseta/strings.json

@@ -7,11 +7,11 @@
       }
     },
     "error": {
-      "cannot_connect": "Failed to connect to Caséta bridge; check your host and certificate configuration."
+      "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]"
     },
     "abort": {
-      "already_configured": "Caséta bridge already configured.",
-      "cannot_connect": "Cancelled setup of Caséta bridge due to connection failure."
+      "already_configured": "[%key:common::config_flow::abort::already_configured_device%]",
+      "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]"
     }
   }
-}
+}