feat(vm): add uptime printable column

[danilrwx]

Description

Add the Uptime printable column for VirtualMachine.

The column is derived from the Running condition transition time using reason=Running. The PhaseAge printable column was removed.

Why do we need it, and what problem does it solve?

Users need to see how long a virtual machine has been running directly in the VM list.

During migration the VM can temporarily receive another condition reason while still running. The controller now keeps the Running reason for a ready VM with an empty VMI ready reason, so the uptime column does not restart after migration.

What is the expected result?

1. Start a virtual machine.
2. Check the Uptime column in kubectl get vm.
3. Migrate the VM.
4. Verify the Uptime column does not start counting from zero again.
5. Verify the PhaseAge column is no longer shown.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: core
type: feature
summary: Add the Uptime printable column for VirtualMachine resources.