removed background task. it wasn't using the same path

Author: Nurhan Turgut

.cirrus.yml

@@ -56,7 +56,7 @@ task:
         - cd web_installers/packages/web_drivers/
         - pub get
         - dart lib/web_driver_installer.dart chromedriver --install-only
-      driver_background_script: ./chromedriver/chromedriver --port=4444
+        - ./chromedriver/chromedriver --port=4444 &
       test_script:
         - cd $E2E_PATH/example/
         - flutter drive -v --target=test_driver/example_e2e_web.dart -d web-server --release --browser-name=chrome