message: test: remove descriptor file during test shutdown for transcoder test
  During coverage the temp folder is shared between tests, so this file
  ends up leaking between tests. This ensures that we clean it up during
  test shut down.
diff: @@ -43,6 +43,9 @@ namespace {
  class GrpcJsonTranscoderFilterTestBase {
  protected:
  GrpcJsonTranscoderFilterTestBase() : api_(Api::createApiForTest()) {}
  + ~GrpcJsonTranscoderFilterTestBase() {
  + TestEnvironment::removePath(TestEnvironment::temporaryPath("envoy_test/proto.descriptor"));
  + }
  Api::ApiPtr api_;
  };
  