IBX-11974: Replaced backported message deduplication with Symfony native implementation and lock release listener

[bnowak]

🎫 Issue	IBX-11974

Related PRs:

• IBX-12084: Added deprecation to DeduplicateStamp in contracts #25
• https://github.com/ibexa/async-content-publishing/pull/7
• https://github.com/ibexa/data-intelligence-layer/pull/35
• https://github.com/ibexa/discounts/pull/343
• IBX-12084: Added Ibexa DXP 6.0 rule set with DeduplicateStamp renamed to Symfony Messenger one rector#50

Description:

Replaces the bundle's own backported message deduplication with Symfony's native implementation, now that the required pieces ship in Symfony 7.4:

• Removed DeduplicateMiddleware, DeduplicateStamp (contracts), DeduplicateStampNormalizer and LockKeyNormalizer in favour of Symfony\Component\Messenger\Middleware\DeduplicateMiddleware, Symfony\Component\Messenger\Stamp\DeduplicateStamp and Symfony\Component\Lock\Serializer\LockKeyNormalizer.
• Dropped the configureLockNormalizerBackport() workaround; the native LockKeyNormalizer is wired directly.
• Added ReleaseDeduplicationLockOnFailureListener, a backport of Symfony 8.1's listener, so the deduplication lock is released once a failed message will no longer be retried — otherwise a new dispatch of the same key stays blocked until the lock TTL expires. It is deliberately wired to the bundle's ibexa.messenger.lock_factory (not Symfony's default lock.factory) so it releases locks stored in the ibexa_messenger_lock_keys table. The backport class and its DI fallback are marked @todo for removal once the minimum Symfony version is >= 8.1.
• Added symfony/lock as an explicit dependency and updated the PHPStan baseline and tests accordingly.

For QA:

Requires deduplication_lock_storage to be enabled.

• Deduplication is unchanged: dispatching two messages carrying the same DeduplicateStamp key results in only one being handled while the lock is held.
• New failure behaviour: when a handled message fails and will not be retried, its deduplication lock is released so the same key can be dispatched and processed again. Previously the key stayed blocked until the lock TTL expired.
• With deduplication_lock_storage disabled, no deduplication middleware or failure listener is registered and behaviour is unchanged.

Documentation:

No client-facing configuration changes — deduplication_lock_storage works exactly as before. Developer-facing upgrade note for 6.0: the deduplication stamp moves from Ibexa\Contracts\Messenger\Stamp\DeduplicateStamp to Symfony's native Symfony\Component\Messenger\Stamp\DeduplicateStamp; code attaching the stamp must switch to the Symfony class.
I think that is also worth mentioning somewhere in docs (during upgrading to version 6.0), that all messages stored in ibexa_messenger_messages should be processed before or removed manually. Some stamps/messages format/contract could be changed between versions and won't work on 6.0, so starting with 6.0 ibexa version this table should be empty to ensure correct processing of background messages.