Long running operations (for example autoscale stacks) can lead to heat
database growth over time. This will remove entries that have been soft
deleted from the heat database.
This adds a cron job that will call heat-manage purge_deleted every 24h.
Change-Id: I3b7c174cc7ed147a8f5700135d3da2e63696008d
Story: 2005020
Task: 29499
0107af60bf