Commit on cancelled subscription in TransactionalOperator::transactional

Prior to this commit, TransactionalOperator::transactional did not close
the transaction when cancelled.

Closes gh-23864

spring-tx/src/main/java/org/springframework/transaction/reactive/TransactionalOperatorImpl.java

@@ -80,7 +80,7 @@ final class TransactionalOperatorImpl implements TransactionalOperator {
 			// Need re-wrapping of ReactiveTransaction until we get hold of the exception
 			// through usingWhen.
 			return status.flatMap(it -> Mono.usingWhen(Mono.just(it), ignore -> mono,
-					this.transactionManager::commit, (res, err) -> Mono.empty(), s -> Mono.empty())
+					this.transactionManager::commit, (res, err) -> Mono.empty(), this.transactionManager::commit)
 					.onErrorResume(ex -> rollbackOnException(it, ex).then(Mono.error(ex))));
 		})
 		.subscriberContext(TransactionContextManager.getOrCreateContext())