Few disk tests were testing support for pure -drive command line
generation for disks now that we assume it for all qemu versions the
cases are obsolete.

Replacements:
disk-readonly-no-device -> disk-readonly-disk
disk-floppy-tray-no-device -> disk-floppy-tray
disk-cdrom-tray-no-device -> disk-cdrom-tray
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>