fix try for external command runs to failed (#7300)

# Description

Fixes: #7298

So `try .. catch` works better on external command failed.

# User-Facing Changes

```
try {nu --testbin fail} catch {print "fail"}
```

After this pr, it will output "fail"

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

Co-authored-by: JT <547158+jntrnr@users.noreply.github.com>

crates/nu-command/tests/commands/try_.rs

@@ -36,3 +36,15 @@ fn catch_can_access_error() {
         assert!(output.err.contains("External command failed"));
     })
 }
+
+#[test]
+fn external_failed_should_be_catched() {
+    Playground::setup("try_catch_test", |dirs, _sandbox| {
+        let output = nu!(
+            cwd: dirs.test(),
+            "try { nu --testbin fail; echo 'success' } catch { echo 'fail' }"
+        );
+
+        assert!(output.out.contains("fail"));
+    })
+}