There were places where we had two links pointing to the same place; one
link would be the name/title of a record, and one link would be under
the "actions" column.
This is confusing, since users would probably expect these links to
point to different places (which is what happens in other tables in the
admin section) and might try to click one of them and then the other
one and be surprised when they found out both of them go to the same
page.
Using `render :nothing` was deprecated, but we never noticed it because
we didn't have a test for the action using it. In Rails 5.1, it raises
an exception.
Using `head :ok` and adding a test for this scenario solves the issue.
