join_default_strictness option set to ALL by default for compatibility

Why it matters

This change ensures backward compatibility by preserving the previous default behavior of the JOIN strictness, preventing unexpected query results or errors when upgrading ClickHouse versions.

How to use it

Users can rely on the default setting of join_default_strictness = ALL for JOIN queries. To customize this behavior, they can set the join_default_strictness parameter to other valid values in the server configuration or query settings.