Background
We want community configuration to be an user-accessible way to manage configuration of Growth team's features. Currently, the Special:EditGrowthConfig form only allows people to edit configuration, and for non-privileged users, it just displays a permission denied error.
Task objective
Instead of erroring out after permission check fails, display the form as usually, but with disabled fields, so users can view, but not edit, the configuration.
Also see " Only administrators or interface-admins should be allowed to edit the form. But all users should be allowed to view the form with its current values." from the parent task, T274031.