[qunit] remove unused 'data_files' parameter Its use was removed when we stoppped pointing firefox at file:// web/test/jstests/ajax_url2.html has never actually been used, it's only been ever mentioned in a QUnit comment.

addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile