[media][fuchsia] Update fuchsia.media.Audio dependency

The fuchsia.media.Audio FIDL service has been migrated to
audio_core.cmx. This change reflects the migration, removing
the injected Audio service and moving it to be a system-service, which
allows Audio to be accessed through the AudioCore system-service
instance.

Bug: fuchsia:57744

Test: media_unittests
Change-Id: I4f68123f72f3db46677d02b194156e5d9f0c211f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2453928Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Payton Bradsky <pbradsky@google.com>
Cr-Commit-Position: refs/heads/master@{#816452}

media/fuchsia/media_unittests.cmx

@@ -3,11 +3,11 @@
     "fuchsia.test": {
       "injected-services": {
         "fuchsia.intl.PropertyProvider": "fuchsia-pkg://fuchsia.com/intl_property_manager#meta/intl_property_manager.cmx",
-        "fuchsia.media.Audio": "fuchsia-pkg://fuchsia.com/audio#meta/audio.cmx",
         "fuchsia.mediacodec.CodecFactory": "fuchsia-pkg://fuchsia.com/codec_factory#meta/codec_factory.cmx"
       },
       "system-services": [
         "fuchsia.sysmem.Allocator",
+        "fuchsia.media.Audio",
         "fuchsia.media.AudioCore"
       ]
     }