To add random exchange in NLJ and SPF when right child is DAS

[zhangyuqin1998]

Task Description

When the data volume in the pipeline is small, the GI operator can only divide a small number of granules, resulting in some workers being idle because they cannot get the granules. This solution inserts a random shuffle operator on GI, and threads that grab granules randomly distribute data to various threads in the cluster, enabling all threads to work and achieving load balancing.
#1494

Solution Description

For now, only Nested Loop Join and SubPlan Filter are considered. Since they both drive right tables with the left table and the right table's query is slower, we need to enable as many threads as possible to lead the right table getting rows in parallel. So we add a random shuffle operator on top of the left child to shuffle the data and enable more threads to work.

Passed Regressions

N/A

Upgrade Compatibility

N/A

Other Information

This is the origin plan. There is obvious task skew.

After adding the random shuffle operator, task skew has been eliminated and and the total query time is reduced

### Release Note

[zhangyuqin1998]

插入 random shuffle 后，会将原来的 dfo 分割成两个 dfo。那么 nlj 所在的 dfo 就会变成纯计算 dfo，它会被调度到 qc 所在到机器上。qc 的机器很可能和左表数据分布在不同的机器上，这会导致左表的所有数据都需要经过网络才能传输给 nlj 算子（比如左表为单分区表，本来不用网络传输就能把数据送给nlj算子）。为了减少网络传输，我们仍然让 nlj 所在的 dfo 和左表的 dfo 分布在同样的机器上。这样，尽管做了 global random shuffle，但还是有一部分数据可以走 local channel。

注释我加在了 exchange info 的结构体里：
/**
When data volume of left table in NLJ is small, there is a task skew due to small granule count.
Therefore, we insert random shuffle above left table to achieve load balancing. Exchange operator
splits DFO into two, and DFO with NLJ is purely computing and scheduled to QC machine. So, data
in left table will be sent to NLJ operator via network. To minimize network transmission, we
schedule DFO with NLJ on machines where left table data is located.
*/

[zhangyuqin1998]

slave mapping 中也可以用 is_related_child_ 这个标记，表示父 dfo 依赖子 dfo 进行构造

[zhangyuqin1998]

这里之前是个bug。父dfo依赖子dfo进行构造时，没有生成p2p id。这会导致slave mapping和join filter一起使用时报4016。在这里生成p2p id之后可以解决这个bug

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