chore: deprecate Nix-based build, remove interactive components (#4895)

Users who prefer the flake build should maintain it externally

.github/workflows/nix-ci.yml

@@ -103,7 +103,7 @@ jobs:
         continue-on-error: true
       - name: Build manual
         run: |
-          nix build $NIX_BUILD_ARGS --update-input lean --no-write-lock-file ./doc#{lean-mdbook,leanInk,alectryon,test,inked} -o push-doc
+          nix build $NIX_BUILD_ARGS --update-input lean --no-write-lock-file ./doc#{lean-mdbook,leanInk,alectryon,inked} -o push-doc
           nix build $NIX_BUILD_ARGS --update-input lean --no-write-lock-file ./doc
           # https://github.com/netlify/cli/issues/1809
           cp -r --dereference ./result ./dist
@@ -146,5 +146,3 @@ jobs:
       - name: Fixup CCache Cache
         run: |
           sudo chown -R $USER /nix/var/cache
-      - name: CCache stats
-        run: CCACHE_DIR=/nix/var/cache/ccache nix run .#nixpkgs.ccache -- -s

doc/flake.nix

@@ -17,7 +17,7 @@
   };
 
   outputs = inputs@{ self, ... }: inputs.flake-utils.lib.eachDefaultSystem (system:
-    with inputs.lean.packages.${system}; with nixpkgs;
+    with inputs.lean.packages.${system}.deprecated; with nixpkgs;
     let
       doc-src = lib.sourceByRegex ../. ["doc.*" "tests(/lean(/beginEndAsMacro.lean)?)?"];
     in {
@@ -44,21 +44,6 @@
           mdbook build -d $out
         '';
       };
-      # We use a separate derivation instead of `checkPhase` so we can push it but not `doc` to the binary cache
-      test = stdenv.mkDerivation {
-        name ="lean-doc-test";
-        src = doc-src;
-        buildInputs = [ lean-mdbook stage1.Lean.lean-package strace ];
-        patchPhase = ''
-          cd doc
-          patchShebangs test
-        '';
-        buildPhase = ''
-          mdbook test
-          touch $out
-        '';
-        dontInstall = true;
-      };
       leanInk = (buildLeanPackage {
         name = "Main";
         src = inputs.leanInk;