test: fix flaky combobox test

Refs: LINK-2581

Author: mrTuomoK

src/domain/event/formSections/classificationSection/__tests__/ClassificationSection.test.tsx

@@ -263,12 +263,18 @@ test('should change keyword', async () => {
   await user.click(keywordOption);
   await user.keyboard('{Escape}');
 
-  await screen.findByRole('button', {
-    name: new RegExp(
-      `1 valittu vaihtoehto.*${getValue(keyword?.name?.fi, '')}`,
-      'i'
-    ),
-  });
+  await waitFor(
+    () =>
+      expect(
+        screen.getByRole('button', {
+          name: new RegExp(
+            `1 valittu vaihtoehto.*${getValue(keyword?.name?.fi, '')}`,
+            'i'
+          ),
+        })
+      ).toBeInTheDocument(),
+    { timeout: 5000 }
+  );
 });
 
 test('should show correct validation error if none main category is selected', async () => {