Change provider references after migration to `rancher` org

# Description When https://github.com/rancher/turtles/issues/2264 is complete, all the forked CAPI repositories will move to the `rancher` GitHub organization. There are multiple references to these projects in different parts of `rancher/turtles` and `rancher/rancher`. Even if the `rancher-sandbox/*` path continues to redirect to `rancher/*`, we need to update the paths accordingly. - `rancher/rancher` `origins.go`: https://github.com/rancher/rancher/blob/33cf4ae2c2abac150309014b07b395beae4bdf94/pkg/image/origins.go#L41 - `rancher/turtles`: https://github.com/search?q=repo%3Arancher%2Fturtles%20rancher-sandbox%2Fcluster-api&type=code