FIX: quoted private topic url respects subfolder install (#25643)

Fixes an issue where private topics that are quoted have an incorrectly formatted url when using a subfolder install.

This update returns a relative url that includes the base_path rather than a combination of base_url + base_path.

spec/lib/pretty_text_spec.rb

@@ -220,7 +220,7 @@ RSpec.describe PrettyText do
           <aside class="quote no-group" data-username="maja" data-post="3" data-topic="#{topic.id}">
           <div class="title">
           <div class="quote-controls"></div>
-          <a href="http://test.localhost/t/#{topic.id}/3">#{I18n.t("on_another_topic")}</a></div>
+          <a href="/t/#{topic.id}/3">#{I18n.t("on_another_topic")}</a></div>
           <blockquote>
           <p>I have nothing to say.</p>
           </blockquote>