Fix ntp module version to an existing tag/branch
Fix ntp module version to an existing tag/branch

The 4.2.x was apparently removed at some point, and this makes the
unit tests fails.

This patch will need to be backported down to Queens.

Change-Id: I6a5a0541d2cccc2e210954c4d3b3c45d24d1d649
Closes-Bug: #1823838

openstack/puppet-tripleo,openstack/puppet-tripleo,openstack/puppet-tripleo