Revert "fix: Always handle the extra response outside of stream, such as the exceptions from bedrock (#1526)" (#1569)

This reverts commit f9ab6934d2.

lua/avante/providers/gemini.lua

@@ -12,6 +12,8 @@ M.role_map = {
 }
 -- M.tokenizer_id = "google/gemma-2b"
 
+function M:is_disable_stream() return false end
+
 function M:parse_messages(opts)
   local contents = {}
   local prev_role = nil