nixos/tests/installer: increase RAM in the VM
nixos/tests/installer: increase RAM in the VM

1G apparently isn't sufficient anymore, at least in swraid case:
https://hydra.nixos.org/build/126561574

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