feat: ability to override default clickhouse config

[alexandrovas]

This PR adds ability to override default Clickhouse config. This can be useful if you need to set TTL for system tables or completely disable them. Without this Clickhouse will filled the disk. The problem is described in more detail here.

Example of values:

clickhouse:
  clickhouse:
    configmap:
      configOverride: |
        <yandex>
            <asynchronous_metric_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </asynchronous_metric_log>
            <query_thread_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </query_thread_log>
            <trace_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </trace_log>
            <part_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </part_log>
            <query_views_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </query_views_log>
            <metric_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </metric_log>
            <query_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </query_log>
            <session_log>
                <ttl>event_date + INTERVAL 1 DAY DELETE</ttl>
            </session_log>
        </yandex>

[Mokto]

Can you maybe add your example here (commented) ?

[alexandrovas]

done :)