change keyfile to key

All files used by kolla-ansible do not have a file ending.
keyfile was added as an anomoly.  I noticed this during a review
that coolsvap had underway where he did a similar thing.  I think
--key is fine.

TrivialFix

Change-Id: I99867a1a04a4dd881dcb2af39946122ea6b7d8a3