ci: no need to check native-image-support gRPC convergence (#666)

I found googleapis/java-shared-dependencies#665 (comment) complains old gRPC version declared by "com.google.cloud:native-image-support" (provided scope). The artifact's gRPC dependency is irrelevant to users.

Author: suztomo

java-shared-dependencies/dependency-convergence-check/src/test/java/com/google/cloud/DependencyConvergenceTest.java

@@ -57,7 +57,10 @@ public void testGrpcConvergence() throws Exception {
             "opencensus-exporter-stats-stackdriver",
             // Because grpc-gcp's gRPC version does not use version range notation, it does not
             // break downstream build
-            "grpc-gcp"));
+            "grpc-gcp",
+            // Because native-image-support's gRPC dependency is provided scope, it does not bring
+            // inconsistent gRPC artifacts to users' class paths.
+            "native-image-support"));
   }
 
   /**