This patch migrates all of the remaining non-unique variable names
in the security role to a pattern that begins with `security_*`.
This will reduce potential variable collisions with other roles.
This is a breaking change for deployers and users who are moving
from the liberty or stable/mitaka branches to master. Release notes
are included with additional details to help with the transition.
Closes-Bug: 1578326
Change-Id: Ib716e81e6fed971b21dc5579ae1a871736e21189
fa2800419e