Fixes #19236 - handle situation when host is destroyed oVirt

The issue was introduced in 4269abbd, where we replaced the
`OVIRT::OvirtException` error by `ActiveRecord::RecordNotFound` in
`find_vm_by_uuid method`, but we haven't updated the corresponding
`rescue` block in `destroy_vm`.
(cherry picked from commit 736cb75f3d41d6a4d847556497574957342ca816)