DOCS-511: Deleted some experimental settings. Removed duplicated description for join_any_take_last_row. (#9639)

* CLICKHOUSEDOCS-511: Removed obsolete settings.

* CLICKHOUSEDOCS-511: Removed duplication for ## join_use_nulls {#join_use_nulls}.
Co-authored-by: NSergei Shtykov <bayonet@yandex-team.ru>