[pve-devel] test: increase migrate_set_downtime only if expected_downtime have more than 30 iterations > 0

[Alexandre Derumier]

This is a test attempt. (apply on top on 3 others patchs).

The idea is to use default 30ms qemu downtime value for migration.

If the expected_downtime is more than 30 iterations > 0  (could be polished, maybe some average stats can be better),
then it's like a never ending migration, so we set to the migrate_set_downtime to the 1s default value. (maybe can we use the expected_downtime average as target value?)

So, We could get the lowest downtime if the memory workload can handle it, 
and for vm with big memory transfert, we upgrade the the value.

This could also help to avoid hang of the monitor(until we set migrate_set_downtime?)