Test suite: make the audio test more robust (refs: #15023)

I did not manage to make it robust enough with Firefox 60 and this test was
never meant to exercise the HTML5 player: it was introduced
(commit:136db50c) to ensure our AppArmor
confinement for Tor Browser did not break audio playback, so let's
do this and not more, just like we're doing for the video test as well.

features/step_definitions/common_steps.rb

@@ -737,10 +737,6 @@ When /^I double-click on the (Tails documentation|Report an Error) launcher on t
   end
 end
 
-When /^I click the HTML5 play button$/ do
-  @screen.wait_and_click("TorBrowserHtml5PlayButton.png", 30)
-end
-
 When /^I (can|cannot) save the current page as "([^"]+[.]html)" to the (.*) directory$/ do |should_work, output_file, output_dir|
   should_work = should_work == 'can' ? true : false
   @screen.type("s", Sikuli::KeyModifier.CTRL)

features/torified_browsing.feature

@@ -41,13 +41,12 @@ Feature: Browsing the web using the Tor Browser
 
   #11592
   @check_tor_leaks @fragile
-  Scenario: Playing HTML5 audio
+  Scenario: Playing an Ogg audio track
     Given I have started Tails from DVD and logged in and the network is connected
     When I start the Tor Browser
     And the Tor Browser loads the startup page
     And no application is playing audio
-    And I open the address "http://www.terrillthompson.com/tests/html5-audio.html" in the Tor Browser
-    And I click the HTML5 play button
+    And I open the address "http://www.terrillthompson.com/music/audio/smallf.ogg" in the Tor Browser
     And 1 application is playing audio after 10 seconds
 
   #10442