Actually disable ai for now (#35327)

Closes https://github.com/zed-industries/zed/issues/35325

* removes Supermaven actions
* removes copilot-related action
* stops re-enabling edit predictions when disabled

Release Notes:

- N/A

crates/agent_ui/src/agent_ui.rs

@@ -265,8 +265,8 @@ fn update_command_palette_filter(cx: &mut App) {
             filter.hide_namespace("agent");
             filter.hide_namespace("assistant");
             filter.hide_namespace("copilot");
+            filter.hide_namespace("supermaven");
             filter.hide_namespace("zed_predict_onboarding");
-
             filter.hide_namespace("edit_prediction");
 
             use editor::actions::{