[DataGridPro] Retain the expansion state with expansion configuration props (#20126)

Author: MBilalShafi

packages/x-data-grid-pro/src/utils/tree/utils.ts

@@ -57,16 +57,20 @@ export const checkGroupChildrenExpansion = (
     return false;
   }
 
+  // If group existed in previous tree, preserve its expansion state
+  if (prevChildrenExpanded !== undefined) {
+    return prevChildrenExpanded;
+  }
+
+  // For new groups, apply default expansion configuration
   let childrenExpanded: boolean;
   if (node.id === GRID_ROOT_GROUP_ID) {
     childrenExpanded = true;
   } else if (isGroupExpandedByDefault) {
     childrenExpanded = isGroupExpandedByDefault(node);
   } else {
     childrenExpanded =
-      defaultGroupingExpansionDepth === -1 ||
-      defaultGroupingExpansionDepth > node.depth ||
-      (prevChildrenExpanded ?? false);
+      defaultGroupingExpansionDepth === -1 || defaultGroupingExpansionDepth > node.depth;
   }
 
   return childrenExpanded;