Eval external command result immediately when using do command with -c (#6645)

* make capture error works better in do command

* remove into string test because we have no way to generate Value::Error for now

crates/nu-command/tests/commands/str_/into_string.rs

@@ -172,18 +172,6 @@ fn from_nothing() {
     assert_eq!(actual.out, "");
 }
 
-#[test]
-fn from_error() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        do -c {$env.use} | into string
-        "#
-    ));
-
-    assert_eq!(actual.out, "nu::shell::column_not_found");
-}
-
 #[test]
 fn int_into_string() {
     let actual = nu!(