test: fix stress test bots (#20138)

This started failing in
https://github.com/microsoft/playwright/pull/20061.

Error:
https://github.com/microsoft/playwright/actions/runs/3906084857/jobs/6673856806#step:8:15

tests/stress/playwright.config.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { defineConfig } from '@playwright/experimental-ct-react';
+import { defineConfig } from '@playwright/test';
 
 export default defineConfig({
   forbidOnly: !!process.env.CI,