migration-test: Rename cmd_src/dst to arch_source/arch_target

This explains better what they do and avoid confussino with
command_src/target.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Tested-by: Cornelia Huck <cohuck@redhat.com> #s390x
Tested-by: Laurent Vivier <lvivier@redhat.com>
1 file changed