lava_server: Enable persistent database connections by default
requested to merge igo95862/lava:collabora/staging-database-persistent-connections into collabora/staging
By default Django opens a new connection to database every query. By setting CONN_MAX_AGE Django will reuse connection for the set amount of seconds.
Set CONN_MAX_AGE to 600 seconds which should be a good balance between performance and memory leak clean-up.