Do no update Gerrit rpm

Gerrit war file is provided by the Gerrit docker image
`yum update` command is updating Gerrit rpm to the newest
Gerrit version.

Change-Id: I8aabc2948cb64c37d971233ca0c80fe1c16a2e39

example-setup/Dockerfile

diff --git a/example-setup/Dockerfile b/example-setup/Dockerfile
index 368f26e..260bf7b 100644
--- a/example-setup/Dockerfile
+++ b/example-setup/Dockerfile
@@ -2,8 +2,7 @@
 
 USER root
 
-RUN yum update -y &&\
-    yum install -y gettext
+RUN yum install -y gettext
 
 ARG JAVA_OPTS='--add-opens java.base/java.net=ALL-UNNAMED --add-opens java.base/java.lang.invoke=ALL-UNNAMED'
 ARG GERRIT_BRANCH=stable-3.5
@@ -21,4 +20,4 @@
 COPY --chown=gerrit:gerrit configs/replication.config.template /var/gerrit/etc/
 COPY --chown=gerrit:gerrit configs/gerrit.config.template /var/gerrit/etc/
 
-ENTRYPOINT [ "/tmp/entrypoint.sh" ]
\ No newline at end of file
+ENTRYPOINT [ "/tmp/entrypoint.sh" ]