fix(acl): make preloadRulesForFolder actually warm the rule cache

[solracsf]

Summary

ACLManager::preloadRulesForFolder() was a no-op: it ran a query that scans every child of a folder and then threw the result away, caching nothing. This fixes it to populate the rule cache as intended, and speeds up the underlying query.

preloadRulesForFolder() called RuleManager::getRulesForFilesByParent() but ignored the returned array:

public function preloadRulesForFolder(int $storageId, int $parentId): void {
    $this->ruleManager->getRulesForFilesByParent($this->user, $storageId, $parentId);
}

getRulesForFilesByParent() has no caching side effect: it just builds and returns rules. So on every trash listing (TrashBackend::listTrashFolder() and getTrashForFolders()), this query scanned every child of the folder (~20k filecache rows on a large folder) and cached nothing. The intent was clearly to warm ACLManager::$ruleCache so the subsequent per-child getACLPermissionsForPath() calls would be cache hits.

Measured ~3.6x faster for the preload query on a 15k-ACL / 20k-child folder (MariaDB 10.11), plus the per-child lookups for children that have rules are now served from cache instead of issuing a query per path.