base-server: disable install of suggests and recommends packages

The options to disable installing suggests and recommended packages
has been in diskimage-builder based images for a long time [1].
However we have no setting for it in our base-server role, meaning
that when launching nodes from cloud-provider images we can be out of
sync on this option.

I6d69ac0bd2ade95fede33c5f82e7df218da9458b is an example where packages
pulled in by suggestions can fail (arguably a packaging issue, but
anyway...)

By enabling this here, we make our control plane servers homogenous
with our diskimage-builder based testing nodes, which is better for
general sanity.  Overall it gives us more control over what's
installed.

[1] https://opendev.org/openstack/diskimage-builder/src/branch/master/diskimage_builder/elements/dpkg/pre-install.d/00-disable-apt-recommends

As I6d69ac0bd2ade95fede33c5f82e7df218da9458b showed, installing
suggested or recommended packages might result in

Change-Id: Id6dcc158944a46fc0ae03b6f1ff372dacd67c2e6

playbooks/roles/base-server/files/95disable-recommends

@@ -0,0 +1,2 @@
+APT::Install-Recommends "0";
+APT::Install-Suggests "0";

playbooks/roles/base-server/tasks/Debian.yaml

@@ -1,3 +1,11 @@
+- name: Disable install of additional recommends and suggests packages
+  copy:
+     mode: 0444
+     src: 95disable-recommends
+     dest: /etc/apt/apt.conf.d/
+     owner: root
+     group: root
+
 # NOTE(ianw) There are ordering issues with this.  Hopefully when
 # we're bionic only we can just remove ntp
 - name: Install NTP

testinfra/test_base.py

@@ -162,3 +162,11 @@ def test_logrotate(host):
         assert cfg_file.exists
         assert cfg_file.contains('/var/log/ansible/run_all_cron.log')
 
+
+def test_no_recommends(host):
+    if host.system_info.distribution in ['ubuntu', 'debian']:
+        cfg_file = host.file("/etc/apt/apt.conf.d/95disable-recommends")
+        assert cfg_file.exists
+
+        assert cfg_file.contains('^APT::Install-Recommends "0"')
+        assert cfg_file.contains('^APT::Install-Suggests "0"')