CI reports [1]:
2021.07.16 09:09:21.040944 [ 172 ] {} <Debug> DiskLocal: Reserving 1.00 MiB on disk `default`, having unreserved 18.00 GiB.
...
2021.07.16 09:09:21.041200 [ 28 ] {} <Debug> default.test_mutations (ReplicatedMergeTreeQueue): Not executing log entry queue-0000000288 of type MUTATE_PART for part 200201_3_3_0_16 because source parts size (217.00 B) is greater than the current maximum (0.00 B).
2021.07.16 09:09:21.041529 [ 171 ] {} <Debug> DiskLocal: Reserving 1.00 MiB on disk `default`, having unreserved 18.00 GiB.
2021.07.16 09:09:21.041838 [ 34 ] {} <Debug> default.test_mutations (ReplicatedMergeTreeQueue): Not executing log entry queue-0000000288 of type MUTATE_PART for part 200201_3_3_0_16 because source parts size (217.00 B) is greater than the current maximum (0.00 B).
2021.07.16 09:09:21.042359 [ 34 ] {} <Debug> default.test_mutations (ReplicatedMergeTreeQueue): Not executing log entry queue-0000000290 of type MUTATE_PART for part 200201_12_12_0_16 because source parts size (237.00 B) is greater than the current maximum (0.00 B).
[1]: https://clickhouse-test-reports.s3.yandex.net/26336/a3653bd665bd59c7c05b0fcd58ea2246e0b69915/integration_tests_(thread).html#fail1
This PR formats all the `*.py` files found under the `tests/integration`
folder. It also reorders the imports and cleans up a bunch of unused
imports.
The formatting also takes care of other things like wrapping lines and
fixing spaces and indents such that the tests look more readable.
