kvm: drop the virtio-blk checks on running disks, which can never match

A virtio-blk disk is written to the domain XML with libvirt's 'virtio' bus, so
the running domain reports it back as VIRTIO and the VIRTIOBLK checks on the
parsed disks are dead code. Attaching to a virtio-blk VM is handled by the
fallback to the VM's rootDiskController detail in getAttachDiskBusType().

LibvirtComputingResource.attachOrDetachDisk() is back to what it was; nothing
calls it.

Author: calvix

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java

@@ -3613,15 +3613,13 @@ public synchronized String attachOrDetachDisk(final Connect conn,
                     if (disk.getDeviceType() == DeviceType.DISK) {
                         if (disk.getBusType() == DiskDef.DiskBus.SCSI) {
                             busT = DiskDef.DiskBus.SCSI;
-                        } else if (disk.getBusType() == DiskDef.DiskBus.VIRTIOBLK) {
-                            busT = DiskDef.DiskBus.VIRTIOBLK;
                         }
                         break;
                     }
                 }
 
                 diskdef = new DiskDef();
-                if (busT == DiskDef.DiskBus.SCSI || busT == DiskDef.DiskBus.VIRTIOBLK) {
+                if (busT == DiskDef.DiskBus.SCSI) {
                     diskdef.setQemuDriver(true);
                     diskdef.setDiscard(DiscardType.UNMAP);
                 }

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/KVMStorageProcessor.java

@@ -1544,8 +1544,6 @@ protected DiskDef.DiskBus getAttachDiskBusType(int deviceId, List<DiskDef> disks
             }
             if (disk.getBusType() == DiskDef.DiskBus.SCSI) {
                 return DiskDef.DiskBus.SCSI;
-            } else if (disk.getBusType() == DiskDef.DiskBus.VIRTIOBLK) {
-                return DiskDef.DiskBus.VIRTIOBLK;
             }
         }
         if (deviceId != 0 && DiskDef.DiskBus.VIRTIOBLK == DiskDef.DiskBus.fromValue(