Revert "add: configs as json GUC for db-root-spec"

This reverts commit f34ca15e84.

test/spec/fixtures/schema.sql

@@ -1866,22 +1866,18 @@ $$ language sql;
 
 create or replace function root() returns "application/openapi+json" as $_$
 declare
-  pgrst_config json := nullif(current_setting('request.root.configs', true), '')::json;
+openapi json = $$
+  {
+    "swagger": "2.0",
+    "info":{
+      "title":"PostgREST API",
+      "description":"This is a dynamic API generated by PostgREST"
+    }
+  }
+$$;
 begin
-  return (
-  select json_build_object(
-    'swagger', '2.0',
-    'info', json_build_object(
-      'title', 'PostgREST API',
-      'description', 'This is a dynamic API generated by PostgREST'
-    ),
-    'pgrst_server_host', pgrst_config->>'server_host',
-    'pgrst_server_port', pgrst_config->>'server_port',
-    'pgrst_openapi_server_proxy_uri', pgrst_config->>'openapi_server_proxy_uri',
-    'pgrst_db_schemas', pgrst_config->'db_schemas',
-    'pgrst_version', pgrst_config->>'version'
-  )::json);
-end;
+  return openapi;
+end
 $_$ language plpgsql;
 
 create or replace function welcome() returns "text/plain" as $$