qa: workunit: handle repo ending in "/ceph-ci"

qa: workunit: handle repo ending in "/ceph-ci"

If the repo ends in "/ceph-ci" it's the same as if it ended in "/ceph-ci.git"

Before this change, the following command was broken if the workunit specified,
e.g., "branch: jewel":

teuthology-suite --ceph-repo https://github.com/ceph/ceph --ceph master
--suite-repo https://github.com/ceph/ceph-ci --suite-branch wip-foo . . .

Fixes: http://tracker.ceph.com/issues/20554
Signed-off-by: Nathan Cutler <ncutler@suse.com>