Fix GH-3080: recover from RedisInvalidSubscriptionException on concurrent pub/sub

[suuuuuuminnnnnn]

Problem

Concurrent addMessageListener + removeMessageListener calls can cause a race
condition in RedisMessageListenerContainer:

1. Thread A calls addMessageListener(listener2, "b") → updates channelMapping
   • listenerTopics, then prepares to call subscribeChannel(["b"])
2. Thread B calls removeMessageListener(listener1, "a") →
   unsubscribeChannel(["a"]) → AbstractSubscription.channels becomes empty
   → closeIfUnsubscribed() → close() → alive = false
3. Thread A resumes → subscribeChannel(["b"]) → checkPulse() →
   alive == false → RedisInvalidSubscriptionException propagates
4. listener2 remains in listenerTopics without an active subscription
   → memory leak

This race only manifests with async drivers (Lettuce). Jedis uses
BlockingSubscriber which sets connection = null after doSubscribe,
making incremental subscribeChannel a no-op.

Fix

In the wasListening branch of addListener(), catch
RedisInvalidSubscriptionException and recover:

try {
    if (!channels.isEmpty()) {
        getRequiredSubscriber().subscribeChannel(...);
    }
    if (!patterns.isEmpty()) {
        getRequiredSubscriber().subscribePattern(...);
    }
} catch (RedisInvalidSubscriptionException ex) {
    stopListening();  // dispose dead connection
    lazyListen();     // fresh connection + re-subscribe all from channelMapping/patternMapping
    return;
}

stopListening() does not change the started flag, so the container remains
running. lazyListen() re-subscribes all topics including the newly added one
(already in channelMapping before the exception).

Testing

Added unit test shouldRecoverWhenSubscriptionDiesOnConcurrentRemove that:

• Simulates the race by making subscriptionMock.subscribe() throw
  RedisInvalidSubscriptionException
• Verifies no exception propagates to the caller
• Verifies recovery triggers a second connection.subscribe() call
• Verifies listenerTopics contains the new listener (no memory leak)
• Verifies isListening() == true after recovery

Closes #3080

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