iotests: 163 is not quick

Testing on ext4, most 'quick' qcow2 tests took less than 5 seconds,
but 163 took more than 20.  Let's remove it from the quick set.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/group

@@ -167,7 +167,7 @@
 159 rw auto quick
 160 rw auto quick
 162 auto quick
-163 rw auto quick
+163 rw auto
 165 rw auto quick
 169 rw auto quick
 170 rw auto quick