Make following tab tests easier to understand

The `click_link` part did nothing other than scrolling to the element,
since in these cases we've got a same-page link and the element it links
to is already on the page. Programmers reading the test would expect the
link to load the page or change to a different tab and would think the
element it links to wasn't there before clicking the link (at least I
did).

spec/system/users_spec.rb

@@ -438,8 +438,8 @@ describe "Users" do
         login_as user
 
         visit user_path(user, filter: "follows")
-        click_link "Citizen proposals"
 
+        expect(page).to have_link "Citizen proposals", href: "#citizen_proposals"
         expect(page).to have_content proposal.title
       end
 
@@ -493,8 +493,8 @@ describe "Users" do
         budget_investment = create(:budget_investment, author: user, followers: [user])
 
         visit user_path(user, filter: "follows")
-        click_link "Investments"
 
+        expect(page).to have_link "Investments", href: "#investments"
         expect(page).to have_link budget_investment.title
       end
     end