Fix creation of iptables rules for non-HA containerized HAproxy

Fix creation of iptables rules for non-HA containerized HAproxy

The introduction of I90253412a5e2cd8e56e74cce3548064c06d022b1 broke the HAproxy
service due to some HAproxy-specific iptables rules being executed during the
puppet config step.

Ensure that no iptables call is performed during the generation of configuration
files. Move those calls to step 1, as implemented in the pacemaker-based
HAproxy service (Ib5a083ba3299a82645f1a0f9da0d482c6b89ee23).

Depends-On: I2d6274d061039a9793ad162ed8e750bd87bf71e9
Closes-Bug: #1697921

Change-Id: Ica3a432ff4a9e7a46df22cddba9ad96e1390b665