Remove modprobe binary from kubelet rkt deployment (#2917)

roles/kubernetes/node/templates/kubelet.rkt.service.j2

@@ -18,7 +18,6 @@ EnvironmentFile={{kube_config_dir}}/kubelet.env
 # stage1-fly mounts /proc /sys /dev so no need to duplicate the mounts
 ExecStart=/usr/bin/rkt run \
 {% if kubelet_load_modules == true %}
-        --volume modprobe,kind=host,source=/usr/sbin/modprobe \
         --volume lib-modules,kind=host,source=/lib/modules \
 {% endif %}
         --volume os-release,kind=host,source=/etc/os-release,readOnly=true \
@@ -51,7 +50,6 @@ ExecStart=/usr/bin/rkt run \
 {% endif %}
 {% endif %}
 {% if kubelet_load_modules == true %}
-        --mount volume=modprobe,target=/usr/sbin/modprobe \
         --mount volume=lib-modules,target=/lib/modules \
 {% endif %}
         --mount volume=etc-cni,target=/etc/cni \