Replace strings in atag component (#40935)

homeassistant/components/atag/strings.json

@@ -6,14 +6,14 @@
         "title": "Connect to the device",
         "data": {
           "host": "[%key:common::config_flow::data::host%]",
-          "email": "Email (Optional)",
+          "email": "[%key:common::config_flow::data::email%]",
           "port": "[%key:common::config_flow::data::port%]"
         }
       }
     },
     "error": {
       "unauthorized": "Pairing denied, check device for auth request",
-      "connection_error": "Failed to connect, please try again"
+      "connection_error": "[%key:common::config_flow::error::cannot_connect%]"
     },
     "abort": {
       "already_configured": "This device has already been added to HomeAssistant"