Fixes SelectLongPressTimeoutPreferenceControllerTest summary check.

This preference was updated in
commit 6c380528
to use "%s" summary and remove the controller's getSummary()
implementation so the old test that checked the controller summary
was failing.

This new version checks the preference's summary directly, but that
seems to require running using the robotest runner instead of unit test
so this test was moved there and now follows patterns used by other
similar tests there.

Fix: 278110568
Test: SelectLongPressTimeoutPreferenceControllerTest
Change-Id: Ib65c823a568ad200ebeae74ad443f32441e5cb73