fix: add multisite mode support to Playwright test environment

Author: imantsk

.github/workflows/playwright-test.yml

@@ -206,9 +206,10 @@ jobs:
       - name: Run Playwright tests
         env:
           WP_E2E_WPCLI_MODE: gh-actions-ci
-          WP_E2E_WP_CONTAINER: ${{ job.services.wordpress.id }}
           WP_E2E_WPCLI_PHAR: /tmp/wp-cli.phar
           WP_E2E_WPCLI_URL: http://localhost:8888
+          WP_E2E_WP_CONTAINER: ${{ job.services.wordpress.id }}
+          WP_E2E_MULTISITE_MODE: ${{ inputs.multisite }}
         run: npm run test:playwright -- --project=${{ inputs.project-name }}
 
       - name: Print WordPress logs on failure