Only enabling rsyslog service if not chroot

Builds running in a chroot are failing when notifying to rsyslog.
Assuming that an env var called FACTER_in_chroot is sent on this
case (as done by disk-image-builder elements), ignore the
declaration and interaction with rsyslog.

Change-Id: Id4c7a3e0c3503904540c59d940b52481d263d5b9
Merge "Only enabling rsyslog service if not chroot"