Function delete_group_members 

pub async fn delete_group_members(
    infra: &InfraContext<'_>,
    token: &str,
    group_name: &str,
    host_expression: &str,
    dry_run: bool,
) -> Result<(), Error>

Resolve host_expression and remove the resolved nodes from group_name.

With dry_run = true, only the resolution runs — no backend mutation. Errors from the per-node deletion abort the loop and surface to the handler, so a partially completed batch is possible.