Restore Instance backup: Failed to mount repository, wrong cifs nas path

### problem

I'm using the NAS backup plugin to backup VMs to a CIFS network share.

When I press "Restore Instance backup" from a VM backup the restore job fails with error "Error restoring VM from backup [{"externalId":"i-4-18-VM\/2026.02.19.12.15.46","name":"back1","uuid":"a3669c69-58d4-4ff3-ab75-e58427b16624","vmId":18}].".

The KVM host agent log reports:
```
2026-02-19 14:29:46,684 WARN [utils.script.Script] (AgentRequest-Handler-1:[]) (logid:2d706b21) Execution of process [1547333] for command [/bin/bash -c sudo mount -t cifs \\bkcloudstack.unipd.it\cloudstack /usr/share/cloudstack-agent/tmp/csbackup.UkQyW10877532893870504995 -o username=cloudstack,password=XXX ] failed.
2026-02-19 14:29:46,684 WARN [utils.script.Script] (AgentRequest-Handler-1:[]) (logid:2d706b21) Process [1547333] for command [/bin/bash -c sudo mount -t cifs \\bkcloudstack.unipd.it\cloudstack /usr/share/cloudstack-agent/tmp/csbackup.UkQyW10877532893870504995 -o username=cloudstack,password=XXX ] encountered the error: [1].
2026-02-19 14:29:46,684 ERROR [resource.wrapper.LibvirtRestoreBackupCommandWrapper] (AgentRequest-Handler-1:[]) (logid:2d706b21) Failed to mount repository {} of type {} to the directory {}
```

The KVM host journal reports:
`Feb 19 14:29:46 emi2 sudo[1547333]: root : PWD=/ ; USER=root ; COMMAND=/bin/mount -t cifs \\bkcloudstack.unipd.itcloudstack /usr/share/cloudstack-agent/tmp/csbackup.UkQyW10877532893870504995 -o username=cloudstack,password=XXX,nobrl`

The network path in the sudo mount command is wrong. It should be something like \\\\\\\bkcloudstack.unipd.it\\\cloudstack or //bkcloudstack.unipd.it/cloudstack

### versions

CloudStack 4.22.0.0
Rocky Linux 10

### The steps to reproduce the bug

1. backup the VM
2. stop the VM
3. select the backup and press "Restore Instance backup"

### What to do about it?

_No response_