chore(server): remove useless client allowGuestDemoWorkspace config (#12988)

#### PR Dependency Tree


* **PR #12988** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Chores**
* Removed the configuration option that allowed guests to access demo
workspaces. This affects related settings in the system configuration
and admin interface.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/core/version/config.ts

@@ -5,7 +5,6 @@ export interface VersionConfig {
     enabled: boolean;
     requiredVersion: string;
   };
-  allowGuestDemoWorkspace?: boolean;
 }
 
 declare global {
@@ -29,8 +28,4 @@ defineModuleConfig('client', {
     desc: "Allowed version range of the app that allowed to access the server. Requires 'client/versionControl.enabled' to be true to take effect.",
     default: '>=0.20.0',
   },
-  allowGuestDemoWorkspace: {
-    desc: 'Allow guests to access demo workspace.',
-    default: true,
-  },
 });