Remove unavailable api backends from fixture

Author: ajhai

fixtures/initial_data.json

@@ -406,21 +406,6 @@
       "config_schema": {}
     }
   },
-  {
-    "model": "apiabstractor.apibackend",
-    "pk": 6,
-    "fields": {
-      "name": "Text-QnA",
-      "slug": "promptly_text_qna",
-      "description": "Answers questions based on the provided information",
-      "api_provider": 4,
-      "api_endpoint": "textqna",
-      "params": {},
-      "input_schema": {},
-      "output_schema": {},
-      "config_schema": {}
-    }
-  },
   {
     "model": "apiabstractor.apibackend",
     "pk": 7,