storage: Track successful creation of LV for removal

storage: Track successful creation of LV for removal

https://bugzilla.redhat.com/show_bug.cgi?id=1233003

Track when the logical volume was successfully created in order to
properly handle the call to virStorageBackendLogicalDeleteVol. It's
possible that the failure to create was because someone created an
LV in the pool outside of libvirt's knowledge. In this case, we don't
want to delete that LV.  A subsequent or future refresh of the pool
will find the volume and cause an earlier failure

Signed-off-by: John Ferlan <jferlan@redhat.com>