Remove tasks that mangle iptables (checksum, NAT)

These tasks have been moved into the lxc_hosts role therefore
they are not needed in here anymore.

Change-Id: I6ec6832e10018427a9f277fe5d502b5547f6006b

test-prepare-host.yml

@@ -235,24 +235,3 @@
         - network_interfaces_rhel  is changed
         - item.alias is defined
       with_items: "{{ bridges }}"
-
-    - name: Determine iptables path
-      shell: which iptables
-      register: _iptables_path
-      tags:
-        - skip_ansible_lint
-
-    - name: Add iptables rule to ensure traffic checksum is correct
-      command: "{{ _iptables_path.stdout }} -A POSTROUTING -t mangle -p tcp -j CHECKSUM --checksum-fill"
-      tags:
-        - skip_ansible_lint
-
-    - name: Add iptables rule to provide internet connectivity to instances
-      command: "{{ _iptables_path.stdout }} -t nat -A POSTROUTING -o eth0 -j MASQUERADE"
-      tags:
-        - skip_ansible_lint
-
-    - name: Add iptables rules for lxc natting
-      command: /usr/local/bin/lxc-system-manage iptables-create
-      tags:
-        - skip_ansible_lint