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.

ext-dict-functions.md note that id_expr can be Tuple

ISSUES-14809 fix MaterializeMySQL empty transaction unstable test case

Improved the description of connecting to MS SQL Server by ODBC.

Return query plan from storage.

Add 'params' column to system.user_directories table.

Attempt to make performance test more reliable

Binary operator monotonicity

Enable more tests with Atomic database

Update default build to gcc-10

Improve Chinese translation of remote.md

Update clickhouse-benchmark.md

Fix access denied on opening file /var/lib/clickhouse/status in integration tests.

changelog for 20.8

Fix signedness conversion monotonicity

Experiment. Allow to turn on fsync on inserts, merges and fetches.