Fix: sidecar cleanup when only `shell-sidecar` is enabled (#4254)

Co-authored-by: Lucas Nogueira <lucas@tauri.studio>

.changes/fix-sidecar-cleanup.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+Kill sidecar processes on app exit even when only the `shell-sidecar` feature is enabled.

core/tauri/src/app.rs

@@ -448,7 +448,7 @@ impl<R: Runtime> AppHandle<R> {
 
   /// Runs necessary cleanup tasks before exiting the process
   fn cleanup_before_exit(&self) {
-    #[cfg(shell_execute)]
+    #[cfg(any(shell_execute, shell_sidecar))]
     {
       crate::api::process::kill_children();
     }