Do not load dm-multipath module from the container

The module must be loaded from the host directly in order
to avoid any SELinux issues.

There are examples in kolla-ansible and tripleo-heat-templates:
- https://review.openstack.org/#/c/605624/
- https://review.openstack.org/#/c/605450/

Change-Id: Ieebb2564e816d83ec4111c211677f0a44488a224
Related-Bug: 1794550

docker/multipathd/Dockerfile.j2

@@ -13,8 +13,5 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
 
 {{ macros.install_packages(multipathd_packages | customizable("packages")) }}
 
-COPY extend_start.sh /usr/local/bin/kolla_extend_start
-RUN chmod 755 /usr/local/bin/kolla_extend_start
-
 {% block multipathd_footer %}{% endblock %}
 {% block footer %}{% endblock %}

docker/multipathd/extend_start.sh

@@ -1,2 +0,0 @@
-#!/bin/bash
-modprobe dm-multipath

releasenotes/notes/do-not-load-modules-9b651e40d3479c39.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - Remove kernel module loading from within containers. This must now be done
+    on the host directly.