SOLR-4708: a follow-up commit that disables the clustering componeny in tests. This is needed because core tests are executed before the contribs are compiled so certain classes are not yet available (unless you already have them locally). An alternative would be to compile everything before any tests are executed, but it seems that it'd add an extra unnecessary overhead to every build.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1512276 13f79535-47bb-0310-9956-ffa450edef68