CI: Remove run-lxc.sh script

This script is maintained in its proper repository, see
@Incubaid/jenkins-lxc. A custom build step has been added to our
Jenkins setup using the "Managed Script" plugin, which fetches the
run-lxc.sh script from its repository, then runs it according to given
$JOB and $BASE arguments.

Template::

    #!/bin/bash -xue

    SCRIPT=/tmp/run-lxc-$BUILD_TAG.sh

    rm -f $SCRIPT
    wget -q -O $SCRIPT http://raw.github.com/Incubaid/jenkins-lxc/master/run-lxc.sh

    exec /bin/bash -xue $SCRIPT $@

See: http://github.com/Incubaid/jenkins-lxc
See: https://wiki.jenkins-ci.org/display/JENKINS/Managed+Script+Plugin