Route all LLM traffic through cloud.zed.dev (#34404)

This PR makes it so all LLM traffic is routed through `cloud.zed.dev`.

We're already routing `llm.zed.dev` to `cloud.zed.dev` on the server,
but we want to standardize on `cloud.zed.dev` moving forward.

Release Notes:

- N/A

crates/language_models/Cargo.toml

@@ -28,7 +28,6 @@ credentials_provider.workspace = true
 copilot.workspace = true
 deepseek = { workspace = true, features = ["schemars"] }
 editor.workspace = true
-feature_flags.workspace = true
 fs.workspace = true
 futures.workspace = true
 google_ai = { workspace = true, features = ["schemars"] }