fix(vmop): prevent Maintenance mode from getting stuck during restore

[danilrwx]

Description

Return reconcile.Result{} instead of nil from two snapshot restore steps to properly complete the reconciliation loop when exiting early.

Changes in:

• exit_maintenance_step.go — return &reconcile.Result{}, nil after setting Maintenance condition to False
• waiting_disk_ready_step.go — return &reconcile.Result{}, nil when VirtualDisk is already Ready

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

When performing a snapshot restore, the VM can get stuck in Maintenance mode indefinitely. This happens because returning nil from a reconcile step causes the controller to skip requeue, but the VM's Maintenance condition was already updated. Without requeue, subsequent reconciliations never process the next steps in the restore pipeline.

What is the expected result?

1. Start VirtualMachineOperation restore
2. VM enters Maintenance mode
3. Snapshot restore completes successfully
4. VM exits Maintenance mode and becomes Ready

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: vm
type: fix
summary: Fixed an issue where a virtual machine could get stuck in the `Maintenance` state during restore from a snapshot.