Fix basic_terminal test flake (#56659)

Missed a test in #56194 with the same issue, and it bit me today :(

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #ISSUE

Release Notes:

- N/A or Added/Fixed/Improved ...

crates/terminal/src/terminal.rs

@@ -2741,10 +2741,7 @@ mod tests {
             completion_rx.recv().await.unwrap(),
             Some(ExitStatus::default())
         );
-        assert_eq!(
-            terminal.update(cx, |term, _| term.get_content()).trim(),
-            "hello"
-        );
+        assert_content_eventually(&terminal, "hello", cx).await;
 
         // Inject additional output directly into the emulator (display-only path)
         terminal.update(cx, |term, cx| {