configurator.py: fix _removeFile to do as described in it's doc string.

Remove file in a non racy way without using the utils.rmFile()
which assumes the file exists.

Change-Id: I0436832ae63891c097038ef2b76606c30c40328a
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1109569
Signed-off-by: Mooli Tayer <mtayer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/28782
Reviewed-by: Oved Ourfali <oourfali@redhat.com>
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>