test: fix flaky toast assertions in draft validation tests (#14615)

### What?

The test "should keep save draft button enabled after validation failure
on update" was intermittently failing in CI with:

```
Error: strict mode violation: locator('.payload-toast-container .toast-error') resolved to 2 elements
```

This occurred because the test clicks the save draft button twice in
quick succession to verify it remains enabled after validation failures.
In slower CI environments, both error toasts were visible
simultaneously, causing Playwright's strict mode to fail.

Author: PatrikKozak

test/field-error-states/e2e.spec.ts

@@ -111,7 +111,9 @@ describe('Field Error States', () => {
       await page.locator('#field-validatedField').fill('This will fail')
 
       await page.click('#action-save-draft')
-      await expect(page.locator('.payload-toast-container .toast-error')).toBeVisible()
+      const errorToast = page.locator('.payload-toast-container .toast-error').first()
+      await expect(errorToast).toBeVisible()
+      await errorToast.locator('button[aria-label="Close toast"]').click()
 
       const saveDraftButton = page.locator('#action-save-draft')
       await expect(saveDraftButton).toBeEnabled()