Unnecessary step in mod/forum/tests/behat/edit_post_student.feature

The step in the "Time limit expires" scenario doesn't quite make sense:

And I add a "Forum" to section "1" and I fill the form with:

Forum name	Test forum name
Forum type	Standard forum for general use
Description	Test forum description

There is already a test forum activity created in the background section of the test, and so the "Forum post subject" discussion refers to that test forum. I think this can be removed.