In case of failed deployment default diagnostic snapshot is empty

[Kyrylo Romanenko]

Actual:
In case of failed deployment default diagnostic snapshot is empty (has size of 0 bytes)
Expected: it should have some data.
Workaround: manually generate a new snapshot.

Steps:
1. Deployed 9.0

2. Upgraded to 9.2 following official instructions:
https://docs.mirantis.com/openstack/fuel/fuel-master/release-notes/update-product/update-prerequisites-9-2.html#update-prerequisites-9-2
https://docs.mirantis.com/openstack/fuel/fuel-master/release-notes/update-product/update-master-9-2.html#update-master-9-2

3. Setted-up cluster with roles: 1 Controller, 1 Compute, 1 Cinder, 1 Ironic.
Neutron VLAN.

4. Started deployment that suffered a failure.