Optimize ipv6servers database and servers stats module

This solve issue: #40060 (closed) by optimizing the ipv6servers database using materialized views that can be persisted into memory. It also splits large view into smaller materialized view that can be updated one by one. An update function is added to the database class of the servers stats module to take care of updating all the views in the right order.

Some views are not called in the website code, but were optimized nevertheless to keep the database views lean. Ex: cw_versions

IMO we can postpone deleting these views when we will be consolidating the metrics data into a single DB.