Dell PowerFlex (Scaleio) connector doesn't handle volume disconnection/unmapping properly

When using Dell PowerFlex (Scaleio) as storage backend for Cinder Volume an issue occurs, when having multiple instances (booted from PowerFlex volumes), doing a hard reboot simultaneously not all VMs start.
Having 60 instances sometimes it is seen, that few instances end up in ERROR state.

for vm in $(openstack server list -f value -c ID); do (openstack server reboot --hard ${vm} &); done

Error in nova compute log for some VMs:
2023-08-11 11:00:57.593 7 ERROR nova.virt.libvirt.driver [req-0a02cc37-6310-46ab-bc61-0b36e552ee32 f8c08487e84e4d3da0fa29cbe72c5dff a6195
d0db62844dc9e58c635f0ae42de - default default] [instance: 67d4f1bc-1899-44da-a384-dd1923146438] Failed to start libvirt guest: libvirt.libvirtError: Cannot access storage file '/dev/disk/by-id/emc-vol-000c86e01b
13e30f-363722d500000046': No such file or directory

The problem is that the os-brick scaleio connector currently doesn't handle the volume unmapping properly.
This means it doesn't wait the necessary amount of time for the old links to disappear.

A potential fix should include a waiting time until the old symlink completely disappears by volume disconnection / unmap before it proceeds further to create a new one and so on....