feat: refactor request body handling to use BodyStorage for improved efficiency

relay/rerank_handler.go

@@ -43,11 +43,11 @@ func RerankHelper(c *gin.Context, info *relaycommon.RelayInfo) (newAPIError *typ
 
 	var requestBody io.Reader
 	if model_setting.GetGlobalSettings().PassThroughRequestEnabled || info.ChannelSetting.PassThroughBodyEnabled {
-		body, err := common.GetRequestBody(c)
+		storage, err := common.GetBodyStorage(c)
 		if err != nil {
 			return types.NewErrorWithStatusCode(err, types.ErrorCodeReadRequestBodyFailed, http.StatusBadRequest, types.ErrOptionWithSkipRetry())
 		}
-		requestBody = bytes.NewBuffer(body)
+		requestBody = common.ReaderOnly(storage)
 	} else {
 		convertedRequest, err := adaptor.ConvertRerankRequest(c, info.RelayMode, *request)
 		if err != nil {