Test suite: re-enable "I can print the current page […]" test (refs: #15336)

I cannot reproduce (in Tails 3.6.2) the Tor Browser bug that made us disable
this test.

features/torified_browsing.feature

@@ -141,8 +141,7 @@ Feature: Browsing the web using the Tor Browser
     When I start the Tor Browser
     When I open the address "file:///home/amnesia/Persistent/Tor Browser/index.html" in the Tor Browser
     Then "Tails - About" has loaded in the Tor Browser
-    # XXX: re-enable once #15336 is fixed
-    # And I can print the current page as "output.pdf" to the persistent Tor Browser directory
+    And I can print the current page as "output.pdf" to the persistent Tor Browser directory
 
   #11585
   @fragile