Fix collection of commcare.celery.heartbeat.blockage_duration metric
Fix collection of commcare.celery.heartbeat.blockage_duration metric

it was failing to send because the value passed in was a timedelta instead of a number of seconds

dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq