Followup on 6e335639: Better suppression of spurious <nowiki/>s

* The regexp testing for nowiki was not properly testing for
  an intervening white-space that acts as a boundary for the regexp.

* Updated an existing parser test that fails without this patch.

* Pages that saw dirty diffs in RT testing are now clean:
  - http://localhost:8000/_rt/dewiki/Gertrude_Schoepperle
  - http://localhost:8000/_rt/eswiki/Amolops_chunganensis
  - http://localhost:8000/_rt/enwiki/Alberta_Forest_Products_Association

Change-Id: I7f0bd2fff3d7fc96ed1042644c097bfc6c1dfe1c