Possible values:
- 1 - Do not merge aggregation states from different servers for distributed query processing - in case it is for certain that there are different keys on different shards.
- 2 - same as 1 but also apply ORDER BY and LIMIT stages

Previous set of QueryProcessingStage does not allow to do this.
But after WithMergeableStateAfterAggregation had been introduced the
following queries can be optimized too under
optimize_distributed_group_by_sharding_key:
- GROUP BY sharding_key LIMIT
- GROUP BY sharding_key LIMIT BY
- GROUP BY sharding_key ORDER BY

And right now it is still not supports:
- WITH TOTALS (looks like it can be supported)
- WITH ROLLUP (looks like it can be supported)
- WITH CUBE
- SETTINGS extremes=1 (looks like it can be supported)
But will be implemented separatelly.

vX: fixes
v2: fix WITH *
v3: fix extremes
v4: fix LIMIT OFFSET (and make a little bit cleaner)
v5: fix HAVING
v6: fix ORDER BY
v7: rebase against 20.7
v8: move out WithMergeableStateAfterAggregation
v9: add optimize_distributed_group_by_sharding_key into test names

Process query until the stage where the aggregate functions were
calculated and finalized.

It will be used for optimize_distributed_group_by_sharding_key.

v2: fix aliases
v3: Fix protocol ABI breakage due to WithMergeableStateAfterAggregation
    Conditions >= for QueryProcessingStage::Enum has been verified, and they
    are ok (in InterpreterSelectQuery).

table function view

DOCSUP-2031: Edit and translate PR to Russian.

DOCSUP-2003: Edit and translate to Russian RabbitMQ description

Less number of threads in builder

Suppress superfluous wget (-nv) output

[RFC] Fix QueryPlan lifetime (for EXPLAIN PIPELINE graph=1) for queries with nested interpreter

ISSUES-4006 add precision argument for DateTime type

[RFC] Fix arrayJoin() capturing in lambda

Fix GRANT ALL statement when executed on a non-global level

Add storages from <user_directories> after ones from <users_config> and <access_control_path>.

fixed Japanese translation for data-types/date.md

Update MergeTree.md

DOCS-744: Fixed the CollapsingMerge description

 fix ALTER LIVE VIEW  [REFRESH] lock issue 

Revert "Documentation about ReplacingMergeTree extended with type DateTime64 for column `ver`"

Stop query execution if exception happened in PipelineExecutor itself.

Revert "Change query event filter and add integration test for empty GTID transaction"

Don't let the fuzzer change max_execution_time

Redis dictionary support for simple Redis requirepass authorization

Added description of the partial_merge_join_optimizations and partial_merge_join_rows_in_right_blocks settings.

Change query event filter and add integration test for empty GTID transaction