Fix wrong result data for constant_duration runner

* The constant_for_duration runner used a collections.deque for storing
results from the scenario runs, this deque had a "maxlen" equal to the
"concurrency" input param, due to this limit, on any new data that is
appended to the deque beyond its "maxlen", old data is discarded. This
was causing results of the runner to be inconsistent.

* Use list instead of deque

Change-Id: Idb9e28cd81e1e34d2af863d9116aa1496bc18c32
Closes-Bug: #1307160
Merge "Fix wrong result data for constant_duration runner"