WebUI: fix accessing wrong variable

Fix up 7131d1bd6b.
PR #21129.

src/webui/www/private/scripts/dynamicTable.js

@@ -122,7 +122,7 @@ window.qBittorrent.DynamicTable ??= (() => {
                     clearTimeout(this.resizeDebounceTimer);
                     this.resizeDebounceTimer = setTimeout(() => {
                         resizeFn(entries);
-                        resizeDebounceTimer = -1;
+                        this.resizeDebounceTimer = -1;
                     }, 100);
                 };