[Flaky] max_connection_age test fix (#37739)

Closes #37739

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/37739 from yashykt:FixMaxConnectionAgeTest 5d677ef875
PiperOrigin-RevId: 675695824

test/core/end2end/tests/max_connection_age.cc

@@ -162,10 +162,12 @@ CORE_END2END_TEST(Http2Test, MaxAgeGracefullyClose) {
     Expect(101, false);
   }
   Step();
-  // The connection is closed gracefully with goaway, the rpc should still be
-  // completed.
-  EXPECT_EQ(server_status.status(), GRPC_STATUS_UNIMPLEMENTED);
-  EXPECT_EQ(server_status.message(), "xyz");
+  if (got_server) {
+    // The connection is closed gracefully with goaway, the rpc should still be
+    // completed.
+    EXPECT_EQ(server_status.status(), GRPC_STATUS_UNIMPLEMENTED);
+    EXPECT_EQ(server_status.message(), "xyz");
+  }
 }
 
 }  // namespace