Description of problem:
When installing an SNO cluster the node cannot transition into "Writing image to disk" from "Waiting for bootkube"

Log message from assisted-service:
time="2021-06-02T06:01:02Z" level=info msg="Update host 3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2 install progress" func="github.com/openshift/assisted-service/internal/bminvento
ry.(*bareMetalInventory).UpdateHostInstallProgress" file="/go/src/github.com/openshift/origin/internal/bminventory/inventory.go:3595" cluster_id=4203eabc-bb7d-4ccf-8907-2278
a627a89a go-id=16380 host_id=3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2 pkg=Inventory request_id=223e31ed-7079-4634-b8e2-5c045e8e1ae4                                              
time="2021-06-02T06:01:02Z" level=error msg="failed to update host 3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2 progress" func="github.com/openshift/assisted-service/internal/bminve
ntory.(*bareMetalInventory).UpdateHostInstallProgress" file="/go/src/github.com/openshift/origin/internal/bminventory/inventory.go:3605" cluster_id=4203eabc-bb7d-4ccf-8907-2
278a627a89a error="Can't assign lower stage \"Writing image to disk\" after host has been in stage \"Waiting for bootkube\"" go-id=16380 host_id=3e7eceb6-0e3f-4ea3-a3ce-fe57
e36e1ac2 pkg=Inventory request_id=223e31ed-7079-4634-b8e2-5c045e8e1ae4


In the cluster events the node transitions into "Rebooting" from "Waiting for bootkube":
{                                                                                                                                                                          
    "cluster_id": "4203eabc-bb7d-4ccf-8907-2278a627a89a",                                                                                                                    
    "event_time": "2021-06-02T05:52:22.715Z",                                                                                                                                
    "host_id": "3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2",                                                                                                                       
    "message": "Host sno: reached installation stage Starting installation: bootstrap",                                                                                      
    "severity": "info"                                                                                                                                                       
  },                                                                                                                                                                         
  {                                                                                                                                                                          
    "cluster_id": "4203eabc-bb7d-4ccf-8907-2278a627a89a",                                                                                                                    
    "event_time": "2021-06-02T05:52:22.789Z",                                                                                                                                
    "host_id": "3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2",                                                                                                                       
    "message": "Host sno: reached installation stage Installing: bootstrap",
    "severity": "info"
  },
  {
    "cluster_id": "4203eabc-bb7d-4ccf-8907-2278a627a89a",
    "event_time": "2021-06-02T05:52:47.397Z",
    "host_id": "3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2",
    "message": "Host sno: reached installation stage Waiting for bootkube",
    "severity": "info"
  },
  {
    "cluster_id": "4203eabc-bb7d-4ccf-8907-2278a627a89a",
    "event_time": "2021-06-02T06:01:02.797Z",
    "host_id": "3e7eceb6-0e3f-4ea3-a3ce-fe57e36e1ac2",
    "message": "Host sno: reached installation stage Rebooting",
    "severity": "info"
  }

Note the cluster installs successfully. 


Version-Release number of selected component (if applicable):
quay.io/ocpmetal/assisted-service@sha256:434617dd691c2f5f1a410ffd9866908fc0e9c72e0c3b26ced3d0d8578180fc3a

Steps to Reproduce:
1. install sno cluster