Strip .catlinks entirely, don't store in auxiliary_text

Categories are already stored as a keyword field so we don't need
them in auxiliary_text.

It's redundant data and probably messes with ranking a tiny bit.

Needs a reindex to remove the extra data.

Change-Id: If65e4f95777b06f357f0fe7e571d3ce653be39e9
Merge "Strip .catlinks entirely, don't store in auxiliary_text"