error about cloud provider support is wrong

https://github.com/kubermatic/operating-system-manager/blob/e0ccd2ce3d42d868d3e85524e9e704bdf707fe67/pkg/controllers/osc/osc_controller.go#L564

Reports the OS name instead of the cloud priovider, leading events that read like this

>operating-system-config-controller OperatingSystemProfile "osp-flatcar" does not support cloud provider "flatcar"

(I tried using Hetzner with custom images, but no dice)

Start at pkg/controllers/osc/osc_controller.go around line 564 and inspect how the unsupported cloud-provider event is assembled. Correct the event so it reports the configured cloud provider rather than the OS name, and verify that the resulting message identifies the provider accurately.

Written by the indexing model from the issue text.