Allow using system node (#18172)

Release Notes:

- (Potentially breaking change) Zed will now use the node installed on
your $PATH (if it is more recent than v18) instead of downloading its
own. You can disable the new behavior with `{"node":
{"disable_path_lookup": true}}` in your settings. We do not yet use
system/project-local node_modules.

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/collab/src/tests/test_server.rs

@@ -21,7 +21,7 @@ use git::GitHostingProviderRegistry;
 use gpui::{BackgroundExecutor, Context, Model, Task, TestAppContext, View, VisualTestContext};
 use http_client::FakeHttpClient;
 use language::LanguageRegistry;
-use node_runtime::FakeNodeRuntime;
+use node_runtime::NodeRuntime;
 use notifications::NotificationStore;
 use parking_lot::Mutex;
 use project::{Project, WorktreeId};
@@ -278,7 +278,7 @@ impl TestServer {
             languages: language_registry,
             fs: fs.clone(),
             build_window_options: |_, _| Default::default(),
-            node_runtime: FakeNodeRuntime::new(),
+            node_runtime: NodeRuntime::unavailable(),
             session,
         });
 
@@ -408,7 +408,7 @@ impl TestServer {
             languages: language_registry,
             fs: fs.clone(),
             build_window_options: |_, _| Default::default(),
-            node_runtime: FakeNodeRuntime::new(),
+            node_runtime: NodeRuntime::unavailable(),
             session,
         });