Revalidate DB duration limits post pgbouncer pool adjustment

The CR [GPRD] Decrease the non-urgent sidekiq pool siz... (gitlab-com/gl-infra/production#20505 - closed) will adjust the pgbouncer pool size, and this might affect client-side DB duration since there might be more waiting time for clients now.

Before we roll out the circuit breaking feature, let's monitor and revalidate whether the current 20k DB seconds/minute limit is still appropriate gitlab-com/gl-infra/observability/team#3859 (comment 2547681794).