nixos/acme: Remove selfsignedDeps from finished targets
nixos/acme: Remove selfsignedDeps from finished targets

selfsignedDeps is already appended to the after and wants
of a cert's renewal service, making these redundant.

You can see this if you run the following command:
systemctl list-dependencies --all --reverse acme-selfsigned-mydomain.com.service

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