Add polygon geographies to Budgets' map

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>

app/controllers/concerns/admin/budget_headings_actions.rb

@@ -59,7 +59,7 @@ module Admin::BudgetHeadingsActions
     end
 
     def allowed_params
-      valid_attributes = [:price, :population, :allow_custom_content, :latitude, :longitude, :max_ballot_lines]
+      valid_attributes = [:price, :population, :allow_custom_content, :latitude, :longitude, :max_ballot_lines, :geozone_id]
 
       [*valid_attributes, translation_params(Budget::Heading)]
     end