v2: rebase against MergeTask
v3: rebase due to conflicts in src/Storages/MergeTree/MergeTreeDataMergerMutator.cpp
v4:
- rebase due to conflicts in src/Storages/MergeTree/MergeTask.cpp
- drop common/scope_guard_safe.h (not used)
From time to time 00975_move_partition_merge_tree test got failed, the
reason is that there is merge in progress that writes data to the source
table again:
<details>
2021.10.12 13:20:40.243839 [ 26955 ] {2dbfea50-639e-49ac-9e82-933a00ea04a3} <Debug> executeQuery: (from [::1]:38060) (comment: 00975_move_partition_merge_tree.sql) ALTER TABLE test_move_partition_src MOVE PARTITION 1 TO TABLE test_move_partition_dest;
2021.10.12 13:20:40.244482 [ 26955 ] {2dbfea50-639e-49ac-9e82-933a00ea04a3} <Debug> test_t1tzb2.test_move_partition_dest (cab3b005-d54b-4cdc-8ab3-b005d54becdc): Cloning part /var/lib/clickhouse/store/467/467d7145-b47e-444e-867d-7145b47ea44e/1_2_2_0/ to /var/lib/clickhouse/store/cab/cab3b005-d54b-4cdc-8ab3-b005d54becdc/tmp_move_from_1_21_21_0
...
2021.10.12 13:20:40.373487 [ 378 ] {} <Trace> test_t1tzb2.test_move_partition_src (467d7145-b47e-444e-867d-7145b47ea44e) (MergerMutator): Merged 6 parts: from 1_2_2_0 to 1_11_11_0
...
2021.10.12 13:20:40.379750 [ 26955 ] {2dbfea50-639e-49ac-9e82-933a00ea04a3} <Debug> test_t1tzb2.test_move_partition_dest (cab3b005-d54b-4cdc-8ab3-b005d54becdc): Cloning part /var/lib/clickhouse/store/467/467d7145-b47e-444e-867d-7145b47ea44e/1_15_15_0/ to /var/lib/clickhouse/store/cab/cab3b005-d54b-4cdc-8ab3-b005d54becdc/tmp_move_from_1_28_28_0
</details>
And also remove cleaning of mutations since this will cause deadlock
after doing MOVE PARTITION under
currently_processing_in_background_mutex.
CI: https://clickhouse-test-reports.s3.yandex.net/0/a59c6b1c8eb47ebf77189a491ee0c3980b38e91c/functional_stateless_tests_
Fixes: 00975_move_partition_merge_tree
