Merge pull request openshift#7238 from r4f4/img-upi-xz

OCPBUGS-14757: images: installer: add xz to the container

Author: openshift-merge-robot

images/installer/Dockerfile.upi.ci.rhel8

@@ -37,7 +37,8 @@ RUN yum update -y && \
       python2-pyyaml \
       python3-pyyaml \
       bind-utils \
-      util-linux && \
+      util-linux \
+      xz && \
     yum clean all && \
     rm -rf /var/cache/yum/* && \
     chmod g+w /etc/passwd