Remove synths that aren't going to be included in 2.4

Author: samaaron

app/server/sonicpi/lib/sonicpi/synthinfo.rb

@@ -4260,8 +4260,8 @@ class BaseInfo
       :dark_ambience => DarkAmbience.new,
       :growl => Growl.new,
       :hollow => Hollow.new,
-      :dark_sea_horn => DarkSeaHorn.new,
-      :singer        => Singer.new,
+#      :dark_sea_horn => DarkSeaHorn.new,
+#      :singer        => Singer.new,
       :mono_player => MonoPlayer.new,
       :stereo_player => StereoPlayer.new,