I implemented a search filter for site settings “plugin:PLUGIN_NAME” which will only show settings of “PLUGIN_NAME”. The Settings on plugins page will use it. Also, a user can combine this with other words, for example: “plugin:PLUGIN_NAME enabled” will show any setting containing word “enabled” for plugin “PLUGIN_NAME”.
https://github.com/discourse/discourse/pull/9692
Hmm 
… I am not sure if I understand your request. It looks like that button is shown no matter if the plugin is enabled or not. 
