Jessie: applications menu handling in the test suite is fragile

Quite often, e.g. when trying to start stuff from the “Internet” submenu, the “Graphics” one ends up being selected instead, and then of course the application can’t be started. Shall we just use the “Activities” view to start applications instead?

Parent Task: #7563 (closed)

Original created by @intrigeri on 9706 (Redmine)