adapts lucene classes for beta

* $role::lucene::configuration::nodes now has the realms in it, updated
  templates accordingly
* factored list of accounts having access on search/indexer boxes by
  regrouping them in the new class role::lucene::admins which would only
  be applied in production.
* require groups::search in lucene::users
* Have /dev/vdb mounted as /a on search boxes and indexer via the new
  class role::lucene::beta
* all.dblist/all-labs.dblist abstraction in templates. Now configured
  via role::configuration::lucene::lsearch_global
* lucene.jobs.sh no more hardcode all.dblist but detects the realm out
  of /etc/wmf-realm to find out the dblist name.
* On beta, also sync InitialiseSettings-labs.php.
* Let us change the WMF.InitialiseSettings lsearch parameter.

Change-Id: Iafefdff4f71d162130b46155902ecd0ee88fab97
Merge "adapts lucene classes for beta" into production