feat(query): support parallel final aggregator

[zhang2014]

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Summary

feat(query): support parallel final aggregator

Fixes #issue

[vercel]

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1 Ignored Deployment

Name	Status	Preview	Updated
databend	⬜️ Ignored (Inspect)		Nov 13, 2022 at 10:51AM (UTC)

[Xuanwo]

ERROR the following files don't have a valid license header: 
src/common/base/src/base/thread_pool.rs
src/common/base/tests/it/thread_pool.rs
src/query/service/src/pipelines/processors/transforms/aggregator/aggregate_info.rs
src/query/service/src/pipelines/processors/transforms/aggregator/aggregator_final_parallel.rs 

[BohuTANG]

Test results on 32C32G:

All table counts:

+----------+
| count()  |
+----------+
| 64000000 |
+----------+

SQL:
select sum(uid) from log group by did,sid ignore_result;
group by did, sid unique key count:1000000, did and sid data type is VARCHAR.

Main branch(nightly v0.8.109):
mysql> select sum(uid) from log group by did,sid ignore_result;
Empty set (20.88 sec)
Read 64000000 rows, 5.74 GiB in 20.659 sec., 3.1 million rows/sec., 284.73 MiB/sec.

This PR(Parallel final aggregator):
mysql> select sum(uid) from log group by did,sid ignore_result;
Empty set (5.64 sec)
Read 64000000 rows, 5.74 GiB in 5.625 sec., 11.38 million rows/sec., 1.02 GiB/sec.

4X faster! 🚀