Fix LiveAudioTranscription sample: replace removed EnsureEpsDownloadedAsync

The sample still referenced the old API that was replaced by
DownloadAndRegisterEpsAsync in the explicit EP download changes.
Also fix Rust formatting (.await on separate line).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bmehta001

samples/cs/live-audio-transcription-example/Program.cs

@@ -20,7 +20,7 @@
 await FoundryLocalManager.CreateAsync(config, Utils.GetAppLogger());
 var mgr = FoundryLocalManager.Instance;
 
-await Utils.RunWithSpinner("Registering execution providers", mgr.EnsureEpsDownloadedAsync());
+await mgr.DownloadAndRegisterEpsAsync();
 
 var catalog = await mgr.GetCatalogAsync();