[GH-647]: Hide UsePreregisteredApplication on on-prem instances (#774)

* [GH-647]: Hide UsePreregisteredApplication on on-prem instances

* [MM-647]: Fixed review comments

Author: Kshitij-Katiyar

plugin.json

@@ -25,8 +25,9 @@
                 "key": "UsePreregisteredApplication",
                 "display_name": "Use Preregistered OAuth Application:",
                 "type": "bool",
-                "help_text": "Set to false if using GitHub Enterprise. When true, instructs the plugin to use the preregistered GitHub OAuth application - application registration steps can be skipped. Requires [Chimera Proxy](https://github.com/mattermost/chimera) URL to be configured for the server. Cannot be used with GitHub enterprise. **This setting is intended to be used with Mattermost Cloud instances only.**",
-                "default": false
+                "help_text": "Set to false if using GitHub Enterprise. When true, instructs the plugin to use the preregistered GitHub OAuth application - application registration steps can be skipped. Requires [Chimera Proxy](https://github.com/mattermost/chimera) URL to be configured for the server. Cannot be used with GitHub enterprise.",
+                "default": false,
+                "hosting": "cloud"
             },
             {
                 "key": "GitHubOAuthClientID",