How to remove the auto generated certificate associated with the App registration created on creation of power pages site?

Question

On creating a power pages site, an app registration is created automatically. This is automatically connected to a certificate which is used as the windows authentication key in the power pages site.

On pressing the Update key button in screenshot 1, the key is updated automatically, and power pages does not provide any option to do so manually. We want to remove this certificate and add a managed identity as a federated credential and use this to make a link between the azure active directory and the power pages site.

we have added the managed identity as a federated credential in this auto generated app registration and also added the managed as a user to the power pages environment. But we are not sure how we can change the value of windows authentication key.

Note - We cannot use certificates or secrets in our project.

Thank you.