Fix another flaky question picker unit test (#42421)

frontend/src/metabase/common/components/QuestionPicker/components/QuestionPicker.unit.spec.tsx

@@ -385,10 +385,12 @@ describe("QuestionPickerModal", () => {
       "true",
     );
 
+    await screen.findByText(/loading/i);
     await screen.findByText(/Didn't find anything/i);
   });
 
   it("should switch back to the default tab when the search query is cleared", async () => {
+    await setupSearchEndpoints([]);
     await setupModal();
 
     const searchInput = await screen.findByPlaceholderText(/search/i);
@@ -407,6 +409,9 @@ describe("QuestionPickerModal", () => {
       "true",
     );
 
+    await screen.findByText(/loading/i);
+    await screen.findByText(/Didn't find anything/i);
+
     await userEvent.clear(searchInput);
 
     expect(