Add CVE-2021-44228 mitigation for ES

This only mitigates the CVE for ES included the pre-packaged
distribution. Users who maintain their own ES (or Solr) installation,
need to apply the mitigation there by themselves.

More information about how JanusGraph is affected by the CVE can be
found here:
https://lists.lfaidata.foundation/g/janusgraph-users/message/6272

The mitigation is recommended in the summary provided by Elasticsearch:
https://discuss.elastic.co/t/apache-log4j2-remote-code-execution-rce-vulnerability-cve-2021-44228-esa-2021-31/291476

Fixes #2891

Signed-off-by: Florian Hockmann <fh@florian-hockmann.de>

janusgraph-dist/src/assembly/static/elasticsearch/config/jvm.options

@@ -89,3 +89,6 @@
 
 # JDK 9+ GC logging
 9-:-Xlog:gc*,gc+age=trace,safepoint:file=../logs/gc.log:utctime,pid,tags:filecount=32,filesize=64m
+
+# CVE-2021-44228 (aka “log4shell”) mitigation 
+-Dlog4j2.formatMsgNoLookups=true