Fixes #37162 - Make sure ESXi check in is reflected in sub facet

[chris1984]

What are the changes introduced in this pull request?

• When the hypervisors checkin from a virt-who report we call the method update_hosts which calls update_subscripiton_facet
• In update_subscripiton_facet we were not declaring the checkin time. We only created a fake subscription_facet for an ESXi host on initial check-in and creation
• Since ESXi does not have rhsmcertd running, it cannot check in like a RHEL host can and update its own subscription_facet
• This makes sure each time we get a report from virt-who we make sure the checkin time in the UI reflects when the report was recieved

Considerations taken when implementing this change?

• There is another bug I am filing with virt-who were after 6 days it just stops sending the report until the service is restarted.
• https://issues.redhat.com/browse/RHEL-25413

What are the testing steps for this pull request?

• Either install virt-who configure plugin either by adding it to forklift in extra plugins, or cloning the repo, adding to bundler.d in the foreman directory and then doing a db:migrate db:seed or spin up a stream box with Beaker
• Check out PR
• Create a config for VMware (Ping me for creds) set it for an hour or lower
• Run the deploy scripts for each one, verify that each report updates in the UI
• Check the UI to make sure the check in time reflects correctly
• Check on it for a few hours with virt-who running on your box and see if you notice it keeping up with the check in

[ianballou]

Verified that host.subscription_facet.last_checkin gets updated when the hypervisor checks in.

Tested via waiting and via restarting virt-who to trigger an upload.