* throttle tests: fix detection of parallel execution
The test wasn't able to detect if too many workers were running.
On my laptop:
- without this change, the 'throttle' target takes ~20 seconds
- with this change, the 'throttle' target takes ~70 seconds
- 1 second isn't long enough to encounter the issue
* Fix throttle test when strategy is 'free' based
'free' strategy allows multiple tasks to be executed in parallel: use
one 'throttledir' per task.
Use 'linear' strategy with a dedicated play for cleanup/setup tasks
* throttle: reset worker idx before queuing a new task
* TestStrategyBase: define task.throttle
otherwise '1' will be used instead of the default value due to the
following expression being equal to '1':
int(templar.template(task_mock.throttle))
Co-authored-by: James Cammarata <jimi@sngx.net>