MapR: do not match "all" if a specific version is available
MapR: do not match "all" if a specific version is available

The "all" entry is a fallback if an entry/override for a specific
version has not been specified.

Change-Id: I5e57a00023cddaed691a2c701dc2e7fbd4726fe4
Closes-Bug: #1686343

openstack/sahara-image-elements,openstack/sahara-image-elements