Use Capybara methods to find/click/check links

We applied the Capybara/SpecificMatcher in commit f52a86b46.  However,
this rule doesn't convert methods finding <a> tags to methods finding
links because <a> tags only count as links when they've got the `href`
attribute. For instance, in the `xss_spec.rb` file we check what happens
when clicking on an anchor tag because we're testing that the `href`
attribute has been removed and so we can't use `click_link`.

So, basically, we can't enable a rule to automatically detect when we're
using `have_css` instead of `have_link`, but we should still do it
because `have_link` adds an extra check which affects accessibility
since it makes sure the tag has the `href` attribute and so it's
recognizable as a link by screen readers.

spec/system/admin/site_customization/information_texts_spec.rb

@@ -55,8 +55,10 @@ describe "Admin custom information texts", :admin do
     visit admin_site_customization_information_texts_path
 
     within("#information-texts-tabs") { click_link "Proposals" }
-    expect(find("a[href=\"/admin/site_customization/information_texts?tab=proposals\"].is-active"))
-      .to have_content "Proposals"
+
+    expect(page).to have_link "Proposals",
+                              href: "/admin/site_customization/information_texts?tab=proposals",
+                              class: "is-active"
   end
 
   context "Globalization" do