Let run_in_login_mode succeed even with broken local config (#10622)

I wondered why this test failed for me.
Turns out my config file is not compatible with current main, but the
error message was useless. I've added `--no-config-file`

tests/shell/mod.rs

@@ -234,7 +234,7 @@ fn run_in_login_mode() {
     let child_output = std::process::Command::new("sh")
         .arg("-c")
         .arg(format!(
-            "{:?} -l -c 'echo $nu.is-login'",
+            "{:?} --no-config-file --login --commands 'echo $nu.is-login'",
             nu_test_support::fs::executable_path()
         ))
         .output()