jenkins: fix trials-cleanup.sh: use 'taken' marker

trials-cleanup.sh was still using the old 'SEEN' marker and thus didn't work.

In trial.py, make sure that *every* trial that is run is marked as taken, not
only those discovered by Trial.next().

Change-Id: I8aa6b2eece5d43266a7c84e6b2974b8fe7f3cda1
2 files changed