Note that in the budgets wizard test we now create district with no
associated geozone, so the text "all city" will appear in the districts
table too, meaning we can't use `within "section", text: "All city" do`
anymore since it would result in an ambiguous match.
Co-Authored-By: Julian Herrero <microweb10@gmail.com>
Co-Authored-By: Javi Martín <javim@elretirao.net>
Since the message might appear several times on the same page, it's
useful to give a bit more context. Besides, usability tests show that
when there's a group with no headings, there's no clear indication on
the page that the group is actually a group and not a heading.
We're also adding some emphasis to the group name in the "Showing
headings" message, to be consistent with the emphasis we've
added the the group name in the "No headings" message.
