lisa.tests.scheduler.eas_behaviour: Detect unsuitable workloads
lisa.tests.scheduler.eas_behaviour: Detect unsuitable workloads

Workloads that will not have any valid placement (satisfying the util of
each task and the capacity of each CPU) are unsuitable to test EAS, so
catch this case and raise CannotCreateError.

credp/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa,credp/lisa