spec: remove uneeded sed's

We have 3 sed command in spec file that are deprecated:

1. > # semanage is not present in the image and virt_use_nfs is on (see rhbz#642209)
   > # remove it from vdsmd startup script to avoid error
   > sed -i 's#/usr/sbin/semanage#/bin/true#' /etc/rc.d/init.d/vdsmd

We don't have semanage command anymore in /etc/rc.d/init.d/vdsmd and ovirt-node
these days provide semanage command.

2. > # libvirtd upstart job is already configured on rhevh
   > sed -i 's/ && start_libvirtd$//' /etc/rc.d/init.d/vdsmd

There is no start_libvirtd anymore in /etc/rc.d/init.d/vdsmd

3. > # chkconfig results (symlinks) cannnot be peristed
   > sed -i 's#/sbin/chkconfig \$srv off##' /etc/rc.d/init.d/vdsmd

No more /sbin/chkconfig $srv off in /etc/rc.d/init.d/vdsmd

Change-Id: I98ecf410204f081b5cea730a87b2aca8786e3a87
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1088218
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>