Fixes#5497
All values must be kept as strings because that's what the previous implementation used to do.
Introduced by 525369e0ce
See https://github.com/vatesfr/xen-orchestra/issues/5497#issuecomment-780314187
```
{
'iscsi-target': {
LUN: {
vendor: 'TrueNAS',
serial: '9eaa394581f3003',
LUNid: 55,
size: 10995116277760,
SCSIid: '36589cfc000000581d40d6d5140d9b9da'
}
}
}
```
fce56cbf4c