At the moment instack-undercloud deletes all workflows with "tripleo" in
the name. This has caused an issue when workflows come from other
locations but shouldn't be deleted.
Adding the tag allows instack-undercloud to delete only workflows with
this tag. It shouldn't delete or touch workflows outside of the
tripleo-common package.
Parital-Bug: #1715389
Change-Id: Ieeb51f8e705b8988fb4d0f5d17d7fce6b5b04f36
(cherry picked from commit e0434359dd)