removes gradebook2/jquery_ui_menu_test

test plan:
* n/a it should never have been added

Change-Id: I170bcc99b6658db46a2a8a713a41390f8c9b91e6
Reviewed-on: https://gerrit.instructure.com/29146
Reviewed-by: Jon Jensen <jon@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Marc LeGendre <marc@instructure.com>
QA-Review: Marc LeGendre <marc@instructure.com>