Security / Giving SSH keys of a Github user is too permissive and risky

### Bug Description

We should not provide SSH private keys, even if it is stored in Kubernetes as secret
https://charmhub.io/github-profiles-automator/configurations#ssh-key-secret-id

SSH keys are too sensitive to be used by applications
SSH keys in Github gives access to ALL repositories of the user

We should instead used token based permissions that is tailored for the application, something more similar to ServiceAccounts in Kubernetes

https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens

### To Reproduce

N/A

### Environment

Edge channel / Revision 200

### Relevant Log Output

```shell
N/A
```

### Additional Context

_No response_