Install iptables in ironic-inspector container

The centos environment ironic-inspector use iptables filter need
install iptables rpm package.

Change-Id: I67081a37977dd6de37a67fcd012e002f2e46743f
Closes-bug: #1906635

docker/ironic-inspector/Dockerfile.j2

@@ -12,6 +12,7 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
 {% if install_type == 'binary' %}
     {% if base_package_type == 'rpm' %}
         {% set ironic_inspector_packages = [
+            'iptables',
             'openstack-ironic-inspector',
             'openstack-ironic-inspector-dnsmasq'
         ] %}
@@ -25,7 +26,9 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
 {{ macros.install_packages(ironic_inspector_packages | customizable("packages")) }}
 
 {% elif install_type == 'source' %}
-    {% if base_package_type == 'deb' %}
+    {% if base_package_type == 'rpm' %}
+        {% set ironic_inspector_packages = ['iptables'] %}
+    {% elif base_package_type == 'deb' %}
         {% set ironic_inspector_packages = ['iptables'] %}
     {% endif %}