Since ExternalLoader::PeriodicUpdater::check_period_sec = 5, and so if
it will be scheduled too early the reload will be skipped, and indeed
this is what you can see in logs [1], the reload is done each 10
seconds, not 5:
2021.01.31 14:20:22.590999 [ 48 ] {} <Trace> ExternalDictionariesLoader: Supposed update time for 'dep_x' is 2021-01-31 14:20:27 (loaded, lifetime [5, 5], no errors)
2021.01.31 14:20:22.591016 [ 48 ] {} <Trace> ExternalDictionariesLoader: Next update time for 'dep_x' was set to 2021-01-31 14:20:27
...
2021.01.31 14:20:32.164882 [ 50 ] {} <Trace> ExternalDictionariesLoader: Start loading object 'dep_x'
[1]: https://clickhouse-test-reports.s3.yandex.net/19584/37797fdf5b30dc97147e73b3ac8ca9025b80aaed/integration_tests_(release).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.
