Remove skip for bug 1439371 on test_volume_boot_pattern

The bug is reported as fixed on master (Liberty). Because of change
Iac44c6a84a39a518f4800483558bbe5223a41359 the ceph job doesn't run on
stable/icehouse or stable/juno, but we'd need to get the cinder fix
backported to proposed/kilo or stable/kilo before we could enable the
test again otherwise it will break stable kilo runs of the ceph job.

Cinder fix: I688898b3841691369d73887f7eabdceb05155db1

Related-Bug: #1439371

Change-Id: Iaeef2aaa3400cdd55a5ecbdfe7d492d7df560289
1 file changed