Remove cert-manager requirement step for Kubewarden version 1.17

[jordojordo]

With the advent of Kubewarden version 1.17, the requirement to have cert-manager will no longer be necessary. During the installation wizard within the UI we should then remove the cert-manager installation step.

[viccuad]

Note though that open-telemetry does depend on cert-manager (I don't remember if the UI already checks for it).

[jordojordo]

The UI does not check for cert-manager within the tracing or metrics checklist, that will have to be an added step.