Fix folder path resolution for instance targets in WriteResourceFileFromObject

Add fallback mechanism to handle folder resolution when rootFolder is empty
(instance targets). First try DirPath with rootFolder, then fallback to
DirPath without rootFolder if the first attempt fails.

pkg/registry/apis/provisioning/resources/resources.go

@@ -183,7 +183,11 @@ func (r *ResourcesManager) WriteResourceFileFromObject(ctx context.Context, obj
 		var ok bool
 		fid, ok = r.folders.Tree().DirPath(folder, rootFolder)
 		if !ok {
-			return "", fmt.Errorf("folder %s NOT found in tree with root: %s", folder, rootFolder)
+			// Fallback: try without rootFolder (for instance targets where rootFolder is empty)
+			fid, ok = r.folders.Tree().DirPath(folder, "")
+			if !ok {
+				return "", fmt.Errorf("folder %s NOT found in tree", folder)
+			}
 		}
 	}