Consolidate html page title output logic into helper (#27563)

app/helpers/application_helper.rb

@@ -91,6 +91,14 @@ module ApplicationHelper
     end
   end
 
+  def html_title
+    safe_join(
+      [content_for(:page_title).to_s.chomp, title]
+      .select(&:present?),
+      ' - '
+    )
+  end
+
   def title
     Rails.env.production? ? site_title : "#{site_title} (Dev)"
   end