This adds integration tests to test the asynchronous_metric_log table
for event_time_microseconds field.

Asynchronous metrics are updated once every 60s, so this setting needs
to be overridden for having those metrics available in time so that the
tests can run. So the `asynchronous_metric_update_period_s` setting is
being overriden to be 2s.

Prepare for clang 11

disallow empty time_zone argument in toStartOf* type of functions

Add retries to integration test_host_ip_change

Fix flaky test 01280_ttl_where_group_by

Stop query execution if exception happened in PipelineExecutor itself.

Add explicit main_configs, user_configs and dictionaries in integration tests

Apply TTL if it's not calculated for part

Support MySQL handler 'set @@xx' settting

* created program in utils

* reset test

* removed additional printings

* refactoring

* fix float generator, fix build

* add readme

* refactor readme

* fixed random int func

* clang format

* fix build

* fix build

* fix PVS, uncrustify

* newline at end of file

* refactor string_type func

* restyle func maps

* support IN operation

* support multiquery

* fix style

* change rand to pcg64

* fix array generation

* fix build

* better

* subqueries

* style

* better

* delete samples.sql
Co-authored-by: NRoman Ilgovskiy <ilgovskiy@yandex-team.ru>

Fix mysql replication GTID event dump format

Wait for clickhouse-server to start in stateful tests

Fix select parts for merge

Check for array size overflow in topK

Website fix bugs

Provide a way to quickly test the website

Remove redundant conditions

Simplify mutations tests

Add missed #include <atomic>

Proxy restart/start/stop/reload of SysVinit to systemd (if it is used)