__wt_cursor_init has a long list of tests for cursor methods that we
don't need, except for get/set-key and get/set-value, almost all of the
methods are explicitly set, it's simpler to set them all then to leave
that code in place.

Two real changes besides the semantic sugar: change the config cursor
reset method from not-supported to a no-op, that's the default, delete
the __cursor_search function (the default search method), no code needed
it.