Complete pending post-transaction callbacks before closing the connection

Problem/Motivation

This is a follow-up to #3569316: Client connection ($clientConnection) must be of type object, null given when deleting a node, not a confirmed regression introduced by that issue. That fix added processing of pending post-transaction callbacks to TransactionManagerBase::commitAll(). However, Connection::commitAll() still calls the manager only when inTransaction() is true.

An explicit Transaction::commitOrRelease() or Transaction::rollBack() can end the database transaction while its post-transaction callbacks remain pending until the Transaction object is destroyed. If that object is still alive when the connection is closed or the shutdown handler runs, the caller skips the manager and therefore skips the callback processing added by #3569316.

This affects deferred cache tag invalidation and other post-transaction callbacks. Data can be saved successfully while a subsequent request still reads stale cached data. In an application-level reproduction, a newly created membership was stored correctly, but the next request was denied access because the permissions cache had not been invalidated.

The issue was reproduced on Drupal 11.4.8 with PHP 8.4.26 and Xdebug 3.5.3 in develop mode in the web server. The kernel regression retains the transaction object explicitly and does not require Xdebug or contributed modules.

Steps to reproduce

Proposed resolution

Remove the inTransaction() condition from Connection::commitAll(), retaining the existing method_exists() compatibility check. The transaction manager already processes pending callbacks when its stack is empty. This allows all three cleanup entry points to complete callbacks while the connection is still valid, including after an explicit commit or rollback.

No additional cache flush, retry, exception suppression, permissions override or alternative transaction implementation is introduced. The attached test covers all three transaction outcomes through all three cleanup entry points, actual cache tag checksums and repeated cleanup followed by transaction destruction.

Remaining tasks

• Review and run the patch against the current target branch and the supported database-driver matrix in Drupal Core CI. The supplied patch is based on and locally verified against Drupal 11.4.8.
• Track response-before-shutdown timing separately. This patch completes callbacks at the existing cleanup boundary; it does not move invalidation before the HTTP response is sent and does not guarantee that a parallel PHP-FPM follow-up request cannot arrive before shutdown. This separate concern is also described in comment #11 of #3569316: Client connection ($clientConnection) must be of type object, null given when deleting a node.
• Do not treat this as a blanket fix for every destruction-order failure. The reproduced skipped-callback condition and application workflow are covered; unrelated PHPUnit CLI shutdown failures and other PHP/database combinations require their own evidence.

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet