Remove redundant HTML map classes

The `map` class is applied to the map element by LeafletJS; using it in
the container led to hacks like adding an `inline` class to fix the fact
that the container was using the `height` rule of the `.map` elements.

Even though we don't add styles for them, I'm adding the `budgets-map`
and `budget-investments-map` HTML classes so these elements can still be
easily selected with CSS and JavaScript.

spec/components/budgets/map_component_spec.rb

@@ -10,7 +10,7 @@ describe Budgets::MapComponent do
 
       render_inline Budgets::MapComponent.new(budget)
 
-      expect(page.first("div.map")).to have_content "located geographically"
+      expect(page.find(".budgets-map")).to have_content "located geographically"
     end
 
     it "is not rendered during the informing phase" do