Set extendwatchlist = 0 for wmf wikis

I don't think this was discussed much (or at all)
to change this and is taking some people by surprise.

extendwatchlist probably needs some more consensus or
at least more communication for wmf deployment.

Bug: 72330
Change-Id: I02b798e6f035f85d7e6a7409b4f039f5403474e8