Remove SLA checks for NovaServers.boot_server_from_volume_and_delete

This benchmark is super unstable and almost fully block rally gate.
The reason is in Nova and Neutron races. So we have to remove until
we fix those projects.

Change-Id: I2188b984183578c5c3f1f42b5e1ba5593692683f
Merge "Remove SLA checks for NovaServers.boot_server_from_volume_and_delete"