Docker: Use CI archive as 2.14 is no longer built

The 2.14 version of the plugin-manager plugin doesn't have the
jenkinsUrl configurable, as opposed to its later versions. Hence
tolerate the exception thrown at runtime as it tries to use its
hard-coded, non-archive URL.

Change-Id: I3f1355936862b240de9dc1741cb8962c3f09fdd4

src/test/docker/gerrit/Dockerfile

diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index e88772c..6e0bbca 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -2,7 +2,7 @@
 
 ENV GERRIT_BRANCH=stable-2.14
 
-ENV GERRIT_CI_URL=https://gerrit-ci.gerritforge.com/job
+ENV GERRIT_CI_URL=https://archive-ci.gerritforge.com/job
 
 USER root