The possibility of filtering for index templates in the cluster state API
had been introduced before there was a dedicated index templates API. This
commit removes this support from the cluster state API, as it was not really
clean, requiring you to specify the metadata and the index templates.
Closes#4954
Instead of specifying what kind of data should be filtered, this commit
streamlines the API to actually specify, what kind of data should be displayed.
This makes its behaviour similar to the other requests, like NodeIndicesStats.
A small feature has been added as well: If you specify an index to select on, not
only the metadata, but also the routing tables are filtered by index in order
to prevent too big cluster states to be returned.
Also the CAT apis have been changed to only return the wanted data in order to keep
network traffic as small as needed.
Tests for the cluster state API filtering have been added as well.
Note: This change breaks backwards compatibility with 0.90!
Closes#4065
Alexander Reelsen
Shay Banon
Clinton Gormley