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.
At startup, server loads configuration files.
However ConfigReloader does not know about already loaded files (files
is empty()), hence it will always reload the configuration just after
server starts (+ 2 seconds, reload timeout).
And on configuration reload the clusters will be re-created, so some
internal stuff will be reseted:
- error_count
- last_used (round_robing)
And if the reload will happen during round_robin test it will start
querying from the beginning, so let's issue config reload just after
start to avoid reload in the middle of the test execution.
