Managed LXCA event streams fill the database to capacity.

[dmetzger57]

Original BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1619374

Description of problem:
With managed LXCAs the CloudForms database fills to capacity quickly. Event streams are not purged quickly enough.

How reproducible:
Manage multiple LXCA instances. Monitor the grow in size of any database partitions

Actual results:
CloudForms becomes unusable

Expected results:
Events are purged periodically and the database remains usable.