try to disable the nocredentials process

Author: ldetmer

google-cloud-spanner/src/test/java/com/google/cloud/spanner/connection/it/ITMutableCredentialsTest.java

@@ -63,9 +63,9 @@ public void testMutableCredentialsUpdateAuthorizationForRunningClient() throws I
     System.out.println("missingPermissionCredentials " + missingPermissionCredentials);
 
     System.out.println("application default " + GoogleCredentials.getApplicationDefault());
-
     SpannerOptions options =
         SpannerOptions.newBuilder()
+                .setEmulatorHost(null)
             .setCredentials(FixedCredentialsProvider.create(mutableCredentials).getCredentials())
             .build();
     System.out.println("initial credentials " + options.getCredentials());