test(load): update error loadtest endpoint to generate hint

This endpoint didn't generate error hint which is not desired
for loadtest.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

Author: taimoorzaeem

test/load/errors.http

@@ -7,7 +7,7 @@ GET http://postgrest/actors?select=*,rolws(*,films(*))
 Prefer: tx=commit
 
 # Misspelled function names
-GET http://postgrest/rpc/call_em_x?name=John
+GET http://postgrest/rpc/call_me_x?name=John
 Prefer: tx=commit
 
 # Permission denied errors