nixos/powertop: wait for hardware to initialize
nixos/powertop: wait for hardware to initialize

We should wait until after `multi-user.target` is triggered to allow
hardware to finish initializing, such as network devices and USB drives.
This ensures `powertop --auto-tune` sets more tunables to "Good".

Fixes #66820

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs