BZ#829110 Remove a "Domain not found" error from stats thread.

Removed redundant code which changed VM status if error occured on
the stats thead.

Change-Id: I1f648b9e3a70dca66cbf056c1f143bc6f0455e4a
Signed-off-by: Gal Hammer <ghammer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/7746
Reviewed-by: Peter V. Saveliev <peet@redhat.com>
Tested-by: Chao Yang <chayang@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>