Bug: Can't use broadcast join when genAddColumnsDf

- 

```
SELECT
sum(vendor_id) over w as w_sum_vendor_id,
max(vendor_id) over w as w_max_vendor_id,
min(vendor_id) over w as w_min_vendor_id,
avg(vendor_id) over w as w_avg_vendor_id,
sum(pickup_longitude) over w as w_sum_pickup_longitude,
max(pickup_longitude) over w as w_max_pickup_longitude,
min(pickup_longitude) over w as w_min_pickup_longitude,
avg(pickup_longitude) over w as w_avg_pickup_longitude,
sum(vendor_id) over w2 as w2_sum_vendor_id,
max(vendor_id) over w2 as w2_max_vendor_id,
min(vendor_id) over w2 as w2_min_vendor_id,
avg(vendor_id) over w2 as w2_avg_vendor_id,
sum(pickup_longitude) over w2 as w2_sum_pickup_longitude,
max(pickup_longitude) over w2 as w2_max_pickup_longitude,
min(pickup_longitude) over w2 as w2_min_pickup_longitude,
avg(pickup_longitude) over w2 as w2_avg_pickup_longitude
FROM taxi
WINDOW w as (partition by vendor_id order by pickup_datetime ROWS BETWEEN 30000 PRECEDING AND CURRENT ROW),
w2 as (partition by vendor_id order by dropoff_datetime ROWS BETWEEN 30000 PRECEDING AND CURRENT ROW)
```
- Normally, it can use broadcast join in window skew optimization, because of small broadcast join table(< 10M)
- However, when remove hint, it will use sortMerge join in window skew optimization because of inaccurate estimates of spark.