We were always passing `officer.user` to this method, so we might as
well pass the officer (since the "officer" is in the name of the method)
and call `officer.user` inside the method.
We're also calling `login_through_form_as` in order to remove the
duplication between these two methods.
In most tests calling this method, we were doing another visit right
after calling this method, so by removing this `visit` call we're making
the tests slightly faster and easier to follow.
We're using the `aria-label` attribute instead of a label because this
is a page where only one field is rendered and the text of the label is
the same as the text of the <h1> tag.
We're using `aria-label` instead of `aria-labelledby` because the former
is supported by Capybara.
