fix: make least-squares buffer large enough to hold json result

src/query/inc/qAggMain.h

@@ -97,7 +97,7 @@ extern "C" {
 #define TSDB_BASE_FUNC_MO TSDB_FUNCSTATE_MO | TSDB_FUNCSTATE_STREAM | TSDB_FUNCSTATE_STABLE | TSDB_FUNCSTATE_OF
 
 #define TSDB_FUNCTIONS_NAME_MAX_LENGTH 16
-#define TSDB_AVG_FUNCTION_INTER_BUFFER_SIZE 50
+#define TSDB_AVG_FUNCTION_INTER_BUFFER_SIZE 128
 
 #define DATA_SET_FLAG ','  // to denote the output area has data, not null value
 #define DATA_SET_FLAG_SIZE sizeof(DATA_SET_FLAG)