Add back synchronization to avoid corrupted subscription input/output streams

- Prevent simultaneous write of subscribe/unsubscribe using the same Connection

- Fix test failure by re-initializing "done" state of SubscriptionTask between runs and adding waits

src/test/java/org/springframework/data/redis/listener/PubSubResubscribeTests.java

@@ -207,6 +207,10 @@ public class PubSubResubscribeTests {
 		container.addMessageListener(adapter,
 				Arrays.asList(new Topic[] { new ChannelTopic(CHANNEL), new PatternTopic("s*") }));
 		container.start();
+
+		// Wait for async subscription tasks to setup
+		Thread.sleep(1000);
+
 		template.convertAndSend("somechannel", "HELLO");
 		template.convertAndSend(CHANNEL, "WORLD");