Remove the assistant2 crate (#12380)

Release Notes:

- N/A

crates/assistant2/src/assistant_settings.rs

@@ -1,26 +0,0 @@
-use schemars::JsonSchema;
-use serde::{Deserialize, Serialize};
-use settings::{Settings, SettingsSources};
-
-#[derive(Default, Debug, Deserialize, Serialize, Clone)]
-pub struct AssistantSettings {
-    pub enabled: bool,
-}
-
-#[derive(Default, Debug, Deserialize, Serialize, Clone, JsonSchema)]
-pub struct AssistantSettingsContent {
-    pub enabled: Option<bool>,
-}
-
-impl Settings for AssistantSettings {
-    const KEY: Option<&'static str> = Some("assistant_v2");
-
-    type FileContent = AssistantSettingsContent;
-
-    fn load(
-        sources: SettingsSources<Self::FileContent>,
-        _: &mut gpui::AppContext,
-    ) -> anyhow::Result<Self> {
-        Ok(sources.json_merge().unwrap_or_else(|_| Default::default()))
-    }
-}