Elasticsearch: Remove support for EOL 6.6 version

As that version is now EOL as of July 29, 2020 ([1]).

Update the config-gerrit documentation accordingly, by linking to the
current Elasticsearch documentation now.

[1] https://www.elastic.co/support/eol

Change-Id: Ied980886440869cc5cdbfc1dd915c0375a2f36e1
3 files changed
tree: 3953d9b0b0bc2e538b3ec39b940346c8af47d3c9
  1. java/
  2. javatests/