sysutils/cfengine*-lts: New ports tracking cfengine*-lts

LTS support is documented at:
https://cfengine.com/supported-versions/

The sysutils/cfengine-lts and sysutils/cfengine-masterfiles-lts
will track cfengine's LTS branch simliarly to devel/subversion-lts
and devel/jenkins-lts tracking their respective upstream LTS
branches. This port must only be updated in accordance to documentation
at https://cfengine.com/supported-versions/.

PR: 274453

(cherry picked from commit 4222609aebc40b65f8a628e2c434e19dfcf38b89)