Enable slow query alerts on database

One of the layers where we can check slowness of the dashboard is directly at the database. We can enable some feature as seen in https://wiki.postgresql.org/wiki/Logging_Difficult_Queries.

Start with the PostgreSQL Logging Difficult Queries reference linked in the issue and inspect the dashboard's database configuration. The issue names no specific file, setting, threshold, or alert destination; clarify those requirements first. Done should mean that slow database queries are logged or alerted as agreed, with a way to verify the behavior.

Written by the indexing model from the issue text.