Improve GraphQL caching for large queries

Pimcore limits caching to a maximum of 50 items per request. For large
GraphQL queries, this limit can easily be exceeded because every object
loaded during query resolution is added to the cache queue with priority 0.
When the queue is truncated, only the top 50 items (by priority) are
retained.

This commit increases the priority of the final GraphQL query result,
ensuring this is more likely to be cached despite the 50-item limit.

src/Service/OutputCacheService.php

@@ -111,7 +111,9 @@ protected function loadFromCache($key)
      */
     protected function saveToCache($key, $item, $tags = []): void
     {
-        \Pimcore\Cache::save($item, $key, $tags, $this->lifetime);
+        # Increase priority to 1 to make it less likely this cache item is evicted from the
+        # queue before actually being written
+        \Pimcore\Cache::save($item, $key, $tags, $this->lifetime, 1);
     }
 
     private function computeKey(Request $request): string