Fixed integration tests: Remove tester service from page initialization (#5618)

Eliminated appending the Tester service to the page's services list in FletTestApp. This may be part of a refactor or cleanup to simplify test app setup.

Author: FeodorFitsner

sdk/python/packages/flet/src/flet/testing/flet_test_app.py

@@ -155,7 +155,6 @@ async def start(self):
         async def main(page: ft.Page):
             self.__page = page
             self.__tester = Tester()
-            page.services.append(self.__tester)
             page.theme_mode = ft.ThemeMode.LIGHT
             page.update()