Remove the assistant2 crate (#12380)

Release Notes:

- N/A

Cargo.lock

@@ -385,49 +385,6 @@ dependencies = [
  "workspace",
 ]
 
-[[package]]
-name = "assistant2"
-version = "0.1.0"
-dependencies = [
- "anyhow",
- "assets",
- "assistant_tooling",
- "chrono",
- "client",
- "collections",
- "editor",
- "env_logger",
- "feature_flags",
- "file_icons",
- "fs",
- "futures 0.3.28",
- "fuzzy",
- "gpui",
- "http 0.1.0",
- "language",
- "languages",
- "log",
- "markdown",
- "node_runtime",
- "open_ai",
- "picker",
- "project",
- "rand 0.8.5",
- "regex",
- "release_channel",
- "schemars",
- "semantic_index",
- "serde",
- "serde_json",
- "settings",
- "story",
- "theme",
- "ui",
- "unindent",
- "util",
- "workspace",
-]
-
 [[package]]
 name = "assistant_slash_command"
 version = "0.1.0"