replaced the :user_filter-attribute with a static list.

There is no proper way of fixing query with reasonable expense: The
attribute on the filters produced all sorts of side-effects in several
tests where query is stubbed incompletely: I reverted back to a simple
list of filters that need special treatment - shame on me, as
code_climate will probably punish me for this, but it will work until query
undergoes major refactoring or dies completely...