Cockpit-machines: cockpit-machines: sensitive data exposure of guest credentials via json argument in process list

A flaw was found in `cockpit-machines`. This vulnerability allows a local attacker with the ability to inspect running processes to expose sensitive guest virtual machine (VM) credentials, such as `rootPassword` and `userPassword`. This occurs when the `install_machine.py` script passes these credentials as a JSON command-line argument during VM creation or installation. The exposure is limited to the period when the installation workflow is active and depends on host process-visibility policies.