Sidekiq has connections open for 1 hour to pgbouncer

During the last failover, we found out that sidekiq keeps connections open to the pgbouncer for 1 hour. ( https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/8462#note_249702570 )

It is needed to understand where and why this connection is not closed. Please provide the MR that closes the connection after using it.