Don't clobber all iSCSI connections during nova cleanup

The existing cleanup_nova() code inadvertently logs out of all iSCSI
connections on the machine because it does not pass the target name
as the -T parameter. This patch changes it to step through the targets
that match the pattern, logging out of each individually, and following
up with a delete op to cleanup the database.

Change-Id: I26c14acbe0e8de18f0e3bf7ad83b37379503e199
Merge "Don't clobber all iSCSI connections during nova cleanup"