delete_on_termination added for VM with cinder volume in 2 tests

Two tests in ServerBootFromVolumeStableRescueTest class don't clean
up volumes after finish. Adding delete_on_termination in block device
mappings (BDM) will clean created BDM cinder volumes when VM is
deleted.

Closes-Bug: #2114714
Change-Id: I4003a5f1e500f92106e1b1d2a0f4a7e9f0047f5d
1 file changed