### What changes were proposed in this pull request?
Currently, AQE uses a very tricky way to trigger and wait for the subqueries:
1. submitting stage calls `QueryStageExec.materialize`
2. `QueryStageExec.materialize` calls `executeQuery`
3. `executeQuery` does some preparation works, which goes to `QueryStageExec.doPrepare`
4. `QueryStageExec.doPrepare` calls `prepare` of shuffle/broadcast, which triggers all the subqueries in this stage
5. `executeQuery` then calls `waitForSubqueries`, which does nothing because `QueryStageExec` itself has no subqueries
6. then we submit the shuffle/broadcast job, without waiting for subqueries
7. for `ShuffleExchangeExec.mapOutputStatisticsFuture`, it calls `child.execute`, which calls `executeQuery` and wait for subqueries in the query tree of `child`
8. The only missing case is: `ShuffleExchangeExec` itself may contain subqueries(repartition expression) and AQE doesn't wait for it.
A simple fix would be overwriting `waitForSubqueries` in `QueryStageExec`, and forward the request to shuffle/broadcast, but this PR proposes a different and probably cleaner way: we follow `execute`/`doExecute` in `SparkPlan`, and add similar APIs in the AQE version of "execute", which gets a future from shuffle/broadcast.
### Why are the changes needed?
bug fix
### Does this PR introduce _any_ user-facing change?
a query fails without the fix and can run now
### How was this patch tested?
new test
Closes#33058 from cloud-fan/aqe.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
(cherry picked from commit 2df67a1a1b)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
b8d3da16b1