mabulla

## Changes - all changes made according to the [Posthog original clickhouse config](https://github.com/PostHog/posthog/blob/b32f8f8b41dc129738e8e5d0c90a2f7299a241d3/docker/clickhouse/config.d/default.xml) - renamed the root-tag in the configs from yandex to clickhouse - added posthog_single_shard posthog_migrations - added...