LVM: Volume is deleted unexpectedly during volume migration

When using LVMISCSIDriver, a volume is unexpectedly deleted during
volume migration operation. This problem only occurs when the
volume_group of backend A and backend B is same value such as
misconfiguration. Even if the configuration is wrong, cinder should
not delete the volume unexpectedly for user.

Closes-Bug: 1404013
Change-Id: I010be0c70589459a488cdef7cd83380eab27c61c
Merge "LVM: Volume is deleted unexpectedly during volume migration"