CallMessageDelegate: fix failing test

The "Check button visibility for swarm call" test is currently broken
for two reasons:
- The joinCallWithVideo button no longer exists as it was removed in
  commit 2dbb5d3ed7.
- The 'visible' property of the joinCallWithAudio button was overriden
  by mistake in commit bef3655f2b.

Change-Id: Ieb48aedf6d63f01d6a7a0a79c124c98ec8e6654b

src/app/commoncomponents/CallMessageDelegate.qml

@@ -151,7 +151,6 @@ SBSMessageBase {
 
             JoinCallButton {
                 id: joinCallWithAudio
-                visible: root.isActive
                 Layout.topMargin: 0.5 // For better sub-pixel rendering
                 objectName: "joinCallWithAudio"
                 source: JamiResources.place_audiocall_24dp_svg

tests/qml/src/tst_CallMessageDelegate.qml

@@ -52,14 +52,11 @@ TestWrapper {
                 uut.confId = "foo"
                 var callLabel = findChild(uut, "callLabel")
                 var joinCallWithAudio = findChild(uut, "joinCallWithAudio")
-                var joinCallWithVideo = findChild(uut, "joinCallWithVideo")
                 compare(callLabel.visible, true)
                 compare(joinCallWithAudio.visible, false)
-                compare(joinCallWithVideo.visible, false)
                 uut.confId = "bar"
                 compare(callLabel.visible, true)
                 compare(joinCallWithAudio.visible, true)
-                compare(joinCallWithVideo.visible, true)
             }
         }
     }