fix: improve error handling in rate limiter and remove unnecessary logging

relay/adaptor/gemini/main.go

@@ -424,8 +424,6 @@ func StreamHandler(c *gin.Context, resp *http.Response) (*model.ErrorWithStatusC
 		data = strings.TrimPrefix(data, "data: ")
 		data = strings.TrimSuffix(data, "\"")
 
-		fmt.Printf(">> gemini response: %s\n", data)
-
 		var geminiResponse ChatResponse
 		err := json.Unmarshal([]byte(data), &geminiResponse)
 		if err != nil {