tests/01r5fail enhance

tests/01r5fail enhance

After removing dev0, the recovery starts because it already has a spare
disk. It's good to check recovery. But it's not right to check recovery
after adding dev3. Because the recovery may finish. It depends on the
recovery performance of the testing machine. If the recovery finishes,
it will fail. But dev3 is only added as a spare disk, we can't expect
there is a recovery happens.

So remove the codes about adding dev3.

Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>