Cirrus config updates

* Set cirrus as secondary on all wikisources and commonswiki.
* Let all wiktionaries, wikimania, and wikimedia wikis have cirrus as a
beta feature.
* Rename $wgCirrusSearchContentReplicaCount to $wmgCirrusSearchReplicaCount
* Setup commons's extra index, file.
* Add support for settings $wgCirrusSearchShardCount because we would like
to change the number of shards from Cirrus's defaults for most wikis.
* Set number of shards for all wikis.  The default is a single shard.
Larger wikis will get more with the goal of each shard being about 2GB
with a bit of room to grow.
* Add warning to $wgContentNamespaces that changing it for Cirrus wikis
will remove the affected namespaces from search results until an full
reindex is completed.

DEPLOYMENT: This change requires the cirrus indexes be built for all wikis
listed until $wmgCirrusIsBuilding in intialize settings.

DEPLOYMENT: This change allows us to do an in place rebuild of all currently
built Cirrus indexes to reduce the number of shards they use which should
reduce load on the Elasticsearch cluster, improve recovery times when a
node drops out, and potentially speed up search and indexing.

Change-Id: If5e0f1bb4bb571a2ae5bb4bedfb52a2a7a10f706
Merge "Cirrus config updates"