Dockerfile: Add delete-project plugin to instances

As it is required to pass the HA plugin e2e test scenarios.

Change-Id: I18d534c88dafb1fa80862ec6f5c2eb38d441acfd
diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index 9b2083d..2451bea 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -13,6 +13,7 @@
 ADD --chown=gerrit:gerrit $GERRIT_CI_URL/plugin-javamelody-bazel-$GERRIT_BRANCH/lastSuccessfulBuild/artifact/bazel-bin/plugins/javamelody/javamelody.jar /var/gerrit/plugins/javamelody.jar
 ADD --chown=gerrit:gerrit $GERRIT_CI_URL/plugin-javamelody-bazel-$GERRIT_BRANCH/lastSuccessfulBuild/artifact/bazel-bin/plugins/javamelody/javamelody-deps_deploy.jar /var/gerrit/lib/javamelody-deps_deploy.jar
 ADD --chown=gerrit:gerrit $GERRIT_CI_URL/plugin-high-availability-bazel-$GERRIT_BRANCH/lastSuccessfulBuild/artifact/bazel-bin/plugins/high-availability/high-availability.jar /var/gerrit/plugins/high-availability.jar
+ADD --chown=gerrit:gerrit $GERRIT_CI_URL/plugin-delete-project-bazel-$GERRIT_BRANCH/lastSuccessfulBuild/artifact/bazel-bin/plugins/delete-project/delete-project.jar /var/gerrit/plugins/delete-project.jar
 
 USER root