applets/clipboard: Don't forward input to filter if it's disabled

When the filter is disabled, don't forward any input to the filter
because it will return nothing.

CCBUG: 450989

applets/clipboard/contents/ui/ClipboardPage.qml

@@ -19,7 +19,7 @@ Menu {
     id: clipboardMenu
     Keys.onPressed: {
         function forwardToFilter() {
-            if (event.text !== "" && !filter.activeFocus) {
+            if (filter.enabled && event.text !== "" && !filter.activeFocus) {
                 clipboardMenu.view.currentIndex = -1
                 if (event.matches(StandardKey.Paste)) {
                     filter.paste();