[Fix] Jest Tests.x-pack/solutions/observability/plugins/exploratory_view/public/components/shared/exploratory_view/components - FilterLabel should render properly (elastic#262207)

Resolves elastic#253320 

**Root cause:** Anti-pattern of nesting findByText (async, retries)
inside waitFor (also retries). The FilterItem component re-renders due
to injectI18n() being called inside the render function, which makes
element references go stale between the findByText resolution and the
toBeInTheDocument() check.

**Fix:** Replaced with waitFor(() => { getByText... }) — synchronous
assertions inside waitFor so all checks run atomically in one retry
cycle. Removed the duplicate assertion and unskipped the test.

Verified: 155/155 consecutive runs pass locally.

Author: ana-davydova

x-pack/solutions/observability/plugins/exploratory_view/public/components/shared/exploratory_view/components/filter_label.test.tsx

@@ -15,8 +15,7 @@ import 'jest-canvas-mock';
 
 jest.setTimeout(10 * 1000);
 
-// FLAKY: https://github.com/elastic/kibana/issues/253320
-describe.skip('FilterLabel', function () {
+describe('FilterLabel', function () {
   mockAppDataView();
 
   const invertFilter = jest.fn();
@@ -38,11 +37,10 @@ describe.skip('FilterLabel', function () {
       />
     );
 
-    await waitFor(async () => {
-      expect(await screen.findByText('elastic-co')).toBeInTheDocument();
-      expect(await screen.findByText('elastic-co')).toBeInTheDocument();
-      expect(await screen.findByText(/web application:/i)).toBeInTheDocument();
-      expect(await screen.findByTitle('Delete Web Application: elastic-co')).toBeInTheDocument();
+    await waitFor(() => {
+      expect(screen.getByText('elastic-co')).toBeInTheDocument();
+      expect(screen.getByText(/web application:/i)).toBeInTheDocument();
+      expect(screen.getByTitle('Delete Web Application: elastic-co')).toBeInTheDocument();
     });
   });