[DevTools] Fix format=txt autocomplete for ES|QL (elastic#192341)

- Closes elastic#189495
- Reference
https://www.elastic.co/guide/en/elasticsearch/reference/current/esql-rest.html#esql-rest-format

<img width="1201" alt="Screenshot 2024-09-09 at 09 51 01"
src="https://github.com/user-attachments/assets/d45d849a-b403-4565-a704-9421b6ba23f1">

src/plugins/console/server/lib/spec_definitions/json/overrides/esql.query.json

@@ -12,7 +12,7 @@
         "csv",
         "json",
         "smile",
-        "text",
+        "txt",
         "tsv",
         "yaml"
       ],