Revert "Add ubuntu impish to libvirt images"

This reverts commit 5da6c41037.

Reason for revert: Nova requires a newer version as well,
instead of building a custom nova ubuntu image for focal,
we can wait for 22.04.

Change-Id: I8eeac66c3905c86d286e9f3bfefabf5ba5fe15c1

libvirt/Dockerfile.ubuntu_impish

@@ -1,24 +0,0 @@
-ARG FROM=docker.io/ubuntu:impish
-FROM ${FROM}
-
-ARG UBUNTU_RELEASE=focal
-ARG CEPH_RELEASE=octopus
-ARG CEPH_RELEASE_TAG=""
-ARG PROJECT=nova
-ARG UID=42424
-ARG GID=42424
-
-ARG CEPH_REPO=http://download.ceph.com/debian-${CEPH_RELEASE}/
-ARG CEPH_KEY=http://download.ceph.com/keys/release.asc
-
-ADD ${CEPH_KEY} /etc/apt/ceph-${CEPH_RELEASE}.key
-COPY ./ubuntu-install-libvirt.sh /tmp/ubuntu-install-libvirt.sh
-RUN set -ex ;\
-    export DEBIAN_FRONTEND=noninteractive ;\
-    apt-get update ;\
-    apt-get install --no-install-recommends -y \
-      apt-transport-https \
-      ca-certificates \
-      gnupg ;\
-    /tmp/ubuntu-install-libvirt.sh ;\
-    rm -rf /tmp/*

zuul.d/libvirt.yaml

@@ -68,13 +68,6 @@
           tags:
             - latest-ubuntu_focal
             - "ubuntu_focal-{{ currentdate }}"
-        # NOTE(gagehugo): Once jammy is released, use that and delete impish
-        - context: libvirt
-          repository: openstackhelm/libvirt
-          dockerfile: Dockerfile.ubuntu_impish
-          tags:
-            - latest-ubuntu_impish
-            - "ubuntu_impish-{{ currentdate }}"
     files: &libvirt_files
       - libvirt/.*
       - zuul.d/libvirt.yaml