[Bug](aggregate) fix bitmap_union return error result in query sql (apache#52033)

Problem Summary:
the bitmap union maybe could call add_batch firstly, and the call add
function,
so if add_batch function not update is_first variable, it's will be loss
data in union.
```
    static void add(BitmapValue& res, const BitmapValue& data, bool& is_first) {
        if (UNLIKELY(is_first)) {
            res = data;
            is_first = false;
        } else {
            res |= data;
        }
    }

    static void add_batch(BitmapValue& res, std::vector<const BitmapValue*>& data, bool& is_first) {
        res.fastunion(data);
        is_first = false;  // before not set this
    }
```

Author: zhangstar333

be/src/vec/aggregate_functions/aggregate_function_bitmap.h

@@ -54,6 +54,7 @@ struct AggregateFunctionBitmapUnionOp {
     template <typename T>
     static void add(BitmapValue& res, const T& data, bool& is_first) {
         res.add(data);
+        is_first = false;
     }
 
     static void add(BitmapValue& res, const BitmapValue& data, bool& is_first) {
@@ -67,6 +68,9 @@ struct AggregateFunctionBitmapUnionOp {
 
     static void add_batch(BitmapValue& res, std::vector<const BitmapValue*>& data, bool& is_first) {
         res.fastunion(data);
+        // after fastunion, res myabe have many datas, so is_first should be false
+        // then call add function will not reset res
+        is_first = false;
     }
 
     static void merge(BitmapValue& res, const BitmapValue& data, bool& is_first) {