nova-compute: trim image a bit on CentOS

libguestfs package fetched kernel-core one which fetched linux-firmware.
We remove the last one and save ~500MB of space:

before/centos-binary-nova-compute: 3.3GB
after1/centos-binary-nova-compute: 2.71GB

Closes-Bug: #1946801
Change-Id: I98cc19c95fcec07dd4e494c14c09938d754f1de0

docker/nova/nova-compute/Dockerfile.j2

@@ -39,7 +39,9 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
             ] %}
         {% endif %}
 
-{{ macros.install_packages(nova_compute_packages | customizable("packages")) }}
+{{ macros.install_packages(nova_compute_packages | customizable("packages")) }} \
+    && dnf remove -y linux-firmware \
+    && dnf clean all
 
     {% elif base_package_type == 'deb' %}
 
@@ -112,6 +114,10 @@ RUN rm -f /etc/nova/nova-compute.conf
             ] %}
         {% endif %}
 
+{{ macros.install_packages(nova_compute_packages | customizable("packages")) }} \
+    && dnf remove -y linux-firmware \
+    && dnf clean all
+
     {% elif base_package_type == 'deb' %}
 
         {% set nova_compute_packages = [
@@ -151,11 +157,11 @@ RUN rm -f /etc/nova/nova-compute.conf
             ] %}
         {% endif %}
 
-RUN mkdir -p /etc/ceph
+RUN mkdir -p /etc/ceph \
+    && {{ macros.install_packages(nova_compute_packages | customizable("packages"), chain=True) }}
 
     {% endif %}
 
-{{ macros.install_packages(nova_compute_packages | customizable("packages")) }}
 
 {% set nova_compute_pip_packages = [
         'oslo-vmware'

releasenotes/notes/bug-1946801-5f3af3c44e567fcf.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    CentOS ``nova-compute`` image has ``linux-firmware`` package removed to save
+    image size by ~500MB.
+    `LP#1926801 <https://launchpad.net/bugs/1926801>`__