[null-safety] remove mockito from route test (#64363)
[null-safety] remove mockito from route test (#64363)

Removes more mockito to unblock migration of all tests to sound null safety. #62886
flutter/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,Hixie/flutter,flutter/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,Hixie/flutter,cbracken/flutter,cbracken/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,Hixie/flutter,cbracken/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,flutter/flutter,flutter/flutter,tvolkert/flutter