fix: enable ALTS bound token (for DirectPath) in the grpc channel provider (#2919)

Author: rockspore

google-cloud-storage/src/main/java/com/google/cloud/storage/GrpcStorageOptions.java

@@ -318,7 +318,10 @@ private Tuple<StorageSettings, Opts<UserProject>> resolveSettingsAndOpts() throw
         InstantiatingGrpcChannelProvider.newBuilder()
             .setEndpoint(endpoint)
             .setAllowNonDefaultServiceAccount(true)
-            .setAttemptDirectPath(attemptDirectPath);
+            .setAttemptDirectPath(attemptDirectPath)
+            .setAllowHardBoundTokenTypes(
+                Collections.singletonList(
+                    InstantiatingGrpcChannelProvider.HardBoundTokenTypes.ALTS));
 
     if (!NoopGrpcInterceptorProvider.INSTANCE.equals(grpcInterceptorProvider)) {
       channelProviderBuilder.setInterceptorProvider(grpcInterceptorProvider);