Evaluate if checking `command_or_script` in worktree is needed during debug launch setup

In the debug launch code, there is a conditional check to see if `command_or_script` exists in the worktree using `worktree.which(command_or_script)`:

```rust
if worktree.which(command_or_script).is_some() {
    arguments.push("--command".to_string());
}
```

It's unclear why this check is here.