Revert "nixos/tests/gitlab: add 32 byte secrets"
Revert "nixos/tests/gitlab: add 32 byte secrets"

This reverts commit d6e0d38b84a00b2ab05324b69e3253d956bb5be7.

We need shorter secrets to continue working, since the earlier
recommendation was too short and there's no way to rotate the them.

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