Add an env var driven expression to the standard deployment scanner scan-interval

Recurring deployment scans in a production container don't make a lot of sense. But our standard container images do rely on the boot time scan, so we don't want to just not use the scanner in images.

A middle ground is to make it easy to turn off the recurring scans by using an expression for our standard config's scanner interval, instead of the static "5000". Default would still be 5000 for compatibility.