Replace substitutable hashes with unlilkey to substitute hashes

[grahamc]

Motivation

This PR replaces a bunch of hashes that are substitutable from cache.nixos.org with hashes that are unlikely to ever substitute.

Context

[github-actions]

🚀 Deployed on https://694b5202fe3f1ef51b07d4b6--determinate-nix.netlify.app

[grahamc]

Checking this diff, none of the store paths mentioned appear load bearing.

[grahamc]

I added this to a flake:

          fodnixRelease = pkgs.fetchFromGitHub {
            owner = "DeterminateSystems";
            repo = "nix-src";
            tag = "v3.15.0";
            hash = "sha256-0ZofAQZNgg5nfIKsVb7g4It6ufmIyLtfFRPOf+6WRkk=";
          };

          fodnixPr = pkgs.fetchFromGitHub {
            owner = "DeterminateSystems";
            repo = "nix-src";
            rev = "6faad2e461def3c2ef3579ae6d8bfd0663400bed";
            hash = "sha256-DEzZ1mU3CqCJ50JvLEu87cwNhGsbmWqOBjCQ19nXDxA=";
          };

and confirmed the release fails:

grahamc@Grahams-MacBook-Pro samples % nix build .#fodnixRelease
warning: Git tree '/Users/grahamc/src/github.com/DeterminateSystems/samples' has uncommitted changes
❌ git+file:///Users/grahamc/src/github.com/DeterminateSystems/samples#fodnixRelease
error: fixed-output derivations must not reference store paths: '/nix/store/cyxjnlx44n7bkg3fz4avscjxm36mc189-source.drv' references 1 distinct paths, e.g. '/nix/store/vj1c3wf9c11a0qs6p3ymfvrnsdgsdcbq-source-stdenv.sh'

while this PR succeeds.