Code review comment for lp:~canonical-platform-qa/webbrowser-app/autopkgtest

Thanks a lot for the reviews pitti/brendand.

I've made a some modifications and pushed them.

Discussed on IRC:
- ADT_NORMAL_USER is not available for tests so keep using $USER
- ubuntu-touch-session doesn't have the x bit so keep using sh -e

I tried needs-recommends instead of explicitly specifying python3-evdev but it broke on the phone so I reverted that part. My gut feeling is that python3-xlib is installed on the phone and confuses autopilot.
We may want to fix autopilot though.