Fix: remove failed queue attributes from cache

[LeeHyungGeol]

Fixes #1239

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

Addresses the issue where failed CompletableFuture<QueueAttributes> objects were cached indefinitely, causing all subsequent requests to fail until service restart.

Problem

When queue creation hasn't propagated to AWS SQS (eventual consistency), the initial failure gets cached permanently. This requires service restart to retry, as reported in #1234:

"Only by restarting the reception server does the look-up start to work."

Solution

Implemented Option A (Minimal Change) as discussed - automatically remove failed futures from cache:

private CompletableFuture<QueueAttributes> getQueueAttributes(String endpointName) {
    CompletableFuture<QueueAttributes> future = this.queueAttributesCache.computeIfAbsent(
        endpointName, newName -> doGetQueueAttributes(endpointName, newName)
    );
    
    future.whenComplete((result, throwable) -> {
        if (throwable != null) {
            this.queueAttributesCache.remove(endpointName);
            logger.debug("Removed failed queue attributes from cache for: {}", endpointName);
        }
    });
    
    return future;
}

Key Benefits:

• Failed futures removed immediately → automatic retry
• Successful futures still cached → performance preserved
• No breaking changes (~5 lines)

💚 How did you test it?

Added 4 comprehensive tests:

• ✅ shouldRemoveFailedQueueAttributesFromCache - Verifies failed cache removal and retry
• ✅ shouldCacheSuccessfulQueueAttributes - Verifies successful cache behavior
• ✅ shouldCacheSuccessfulQueueAttributesWithAttributeNames - Verifies cache with config options
• ✅ shouldCreateSeparateObservationsForRetryAfterCacheFailure - Verifies observability tracking

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• I updated reference documentation to reflect the change
• All tests passing
• No breaking changes

🔮 Next steps

Potential improvements for follow-up PRs:

• TTL-based cache expiration
• Rate limiting for failed attempts
• Retry mechanism for SqsMessageListenerContainer

[tomazfernandes]

Thanks for the PR @LeeHyungGeol! Looking forward to more!