#11 Reduce frequency for heartbeat on DIU

One or more processes on the DIU issue 'heartbeat' debug messages which get passed back to the `diagnostic_log` table in the database. The frequency is set to 1 sec which is too much. Reduce this to at least 10 seconds. | | | |---|---| | priority | medium | | work estimate | 1 work unit |

resolved in 7c3e3be3ec617878b68fb588faf7a92d8a856583