ceph-devstack can't start containers in vm where /sys/class/dmi/id/board_serial is missing

[kshtsk]

The '/sys/class/dmi/id/board_serial' is not necessary exists in nested virtualization configuration so ceph-devstack should not rely on it

[kshtsk]

$ sudo ls -la /sys/class/dmi/id/
total 0
drwxr-xr-x 3 root root    0 Sep 15 16:21 .
drwxr-xr-x 3 root root    0 Sep 15 16:21 ..
-r--r--r-- 1 root root 4096 Sep 15 17:31 bios_date
-r--r--r-- 1 root root 4096 Sep 15 17:31 bios_release
-r--r--r-- 1 root root 4096 Sep 15 17:31 bios_vendor
-r--r--r-- 1 root root 4096 Sep 15 17:31 bios_version
-r--r--r-- 1 root root 4096 Sep 15 16:21 chassis_asset_tag
-r-------- 1 root root 4096 Sep 15 17:30 chassis_serial
-r--r--r-- 1 root root 4096 Sep 15 17:31 chassis_type
-r--r--r-- 1 root root 4096 Sep 15 17:31 chassis_vendor
-r--r--r-- 1 root root 4096 Sep 15 17:31 chassis_version
-r--r--r-- 1 root root 4096 Sep 15 16:21 modalias
drwxr-xr-x 2 root root    0 Sep 15 17:31 power
-r--r--r-- 1 root root 4096 Sep 15 17:31 product_family
-r--r--r-- 1 root root 4096 Sep 15 16:21 product_name
-r-------- 1 root root 4096 Sep 15 16:21 product_serial
-r--r--r-- 1 root root 4096 Sep 15 16:21 product_sku
-r-------- 1 root root 4096 Sep 15 16:21 product_uuid
-r--r--r-- 1 root root 4096 Sep 15 16:21 product_version
lrwxrwxrwx 1 root root    0 Sep 15 16:21 subsystem -> ../../../../class/dmi
-r--r--r-- 1 root root 4096 Sep 15 16:21 sys_vendor
-rw-r--r-- 1 root root 4096 Sep 15 16:21 uevent

and by the way:

/sys/class/dmi/id/chassis_serial
/sys/class/dmi/id/product_serial

are empty