test(radarr): name the updates loading test after its neighbours

The Radarr system details tests prefix their loading cases with renders_. This one was copied verbatim from the other trees and did not match. Rename it and its snapshot to fit, leaving the sibling trees alone.

src/ui/radarr_ui/system/system_details_ui_tests.rs

@@ -88,7 +88,7 @@ mod tests {
     }
 
     #[test]
-    fn test_system_details_ui_updates_popup_is_loading_when_updates_are_present() {
+    fn test_system_details_ui_renders_updates_loading_when_updates_are_present() {
       let mut app = App::test_default_fully_populated();
       app.is_loading = true;
       app.push_navigation_stack(ActiveRadarrBlock::SystemUpdates.into());