Disable Python-based UI tests.

We can no longer support Python-based UI tests without significant effort. Hence
disabling them. The complication arises when C apps want to use Python across
several threads.

Change-Id: I70517a7269df6b00609030c4694fac05309e8867
Merge topic 'refactor_python_interpretor' into next

76379b3 Disable Python-based UI tests.