Reload remote_url_allow_hosts on config update

Why it matters

This feature allows users to modify the list of allowed hosts for outgoing HTTP connections by updating the remote_url_allow_hosts configuration and having the changes take effect immediately. It eliminates the need to restart the ClickHouse server when updating this security filter, improving operational flexibility and reducing downtime.

How to use it

To apply this feature, update the remote_url_allow_hosts setting in the ClickHouse configuration file. The new settings will be automatically reloaded and applied to outgoing connection filtering without requiring a server restart.