Remove the javaMelody plugin fromk docker setup

This change removes the plugin as it is not used for the purpose of the
gc-conductor tests.

Change-Id: I68eaa0396ccd6bb091b739da817538e8ba6feccc

src/test/docker/gerrit/Dockerfile

diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index 34c1f8f..9c9d65e 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -4,10 +4,8 @@
 
 ENV GERRIT_BRANCH=stable-3.5
 
-ENV GERRIT_CI_URL=https://gerrit-ci.gerritforge.com/job
 ARG POSTGRES_DRIVER
 
-ADD --chown=gerrit:gerrit $GERRIT_CI_URL/plugin-javamelody-bazel-master-$GERRIT_BRANCH/lastSuccessfulBuild/artifact/bazel-bin/plugins/javamelody/javamelody.jar /var/gerrit/plugins/javamelody.jar
 ADD --chown=gerrit:gerrit $POSTGRES_DRIVER /var/gerrit/lib/postgresql-42.2.5.jar
 
 USER root