Unsubscribe only once on Subscription.close().

We now unsubscribe from Redis only once when closing a Subscription object to avoid duplicate traffic and unexpected Redis responses.

Jedis does not have a mechanism to consume the additional unsubscribe response which leaves protocol frames on the InputStream leading to a corrupt state.

Closes #2355

src/main/java/org/springframework/data/redis/connection/jedis/JedisSubscription.java

@@ -38,6 +38,7 @@ class JedisSubscription extends AbstractSubscription {
 
 	@Override
 	protected void doClose() {
+
 		if (!getChannels().isEmpty()) {
 			jedisPubSub.unsubscribe();
 		}

src/main/java/org/springframework/data/redis/connection/lettuce/LettuceSubscription.java

@@ -76,10 +76,6 @@ public class LettuceSubscription extends AbstractSubscription {
 	@Override
 	protected void doClose() {
 
-		if (!isAlive()) {
-			return;
-		}
-
 		List<CompletableFuture<?>> futures = new ArrayList<>();
 
 		if (!getChannels().isEmpty()) {

src/main/java/org/springframework/data/redis/connection/util/AbstractSubscription.java

@@ -99,8 +99,19 @@ public abstract class AbstractSubscription implements Subscription {
 
 	@Override
 	public void close() {
-		doClose();
-		alive.set(false);
+
+		if (alive.compareAndSet(true, false)) {
+
+			doClose();
+
+			synchronized (channels) {
+				channels.clear();
+			}
+
+			synchronized (patterns) {
+				patterns.clear();
+			}
+		}
 	}
 
 	/**