chore: Update nix workflow and flake.lock

- Update the version of `cachix/install-nix-action` to v27 in Nix workflow
- Add setup for Attic cache and enable magic Nix cache in the workflow
- Update `flake.lock`
- Remove container build and push

Signed-off-by: Harald Hoyer <harald@matterlabs.dev>

packages/container-vault-auth-tee.nix

@@ -1,26 +0,0 @@
-{ pkgs
-, vat
-, vault
-, ...
-}:
-pkgs.dockerTools.buildLayeredImage {
-  name = "vault-auth-tee";
-  tag = "test";
-
-  config.Entrypoint = [ "/bin/sh" ];
-
-  contents = pkgs.buildEnv {
-    name = "image-root";
-
-    paths = with pkgs.dockerTools; [
-      vat.vault-auth-tee
-      vat.vault-auth-tee.sha
-      vault
-      usrBinEnv
-      binSh
-      caCertificates
-      fakeNss
-    ];
-    pathsToLink = [ "/bin" "/etc" "/share" ];
-  };
-}