chore(3p/sources): bump nixpkgs channels & overlays

* 3p/buzz: delete package

  This is unused, old, and uses an insecure version of OpenSSL which
  broke eval.

* 3p/overlays: remove nvd patch

  Newer versions of nvd are compatible with Nix 2.3 by default.

* users/grfn/system/home: remove explicit rust-analyser package

  This conflicts with `rustup`, causing eval failures, as the wrapper
  seems to now be included in `rustup` by default.

* users/grfn/system: temporarily disable ISO builds

  They were broken upstream in nixpkgs by a change to stdenv/setup.sh,
  being fixed in https://github.com/NixOS/nixpkgs/pull/234883

Change-Id: I0eea99ec98f4e73e615c012ffae1d0e37122e73b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8585
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: tazjin <tazjin@tvl.su>

third_party/overlays/patches/nvd-nix-2.3.patch

@@ -1,12 +0,0 @@
-diff --git a/src/nvd b/src/nvd
-index 4caf646..793fc60 100755
---- a/src/nvd
-+++ b/src/nvd
-@@ -440,7 +440,6 @@ def query_closure_disk_usage_bytes(target: Path) -> Optional[int]:
-         stdout = subprocess.run(
-                 [
-                     make_nix_bin_path("nix"), "path-info",
--                    "--extra-experimental-features", "nix-command",
-                     "--closure-size", target_str,
-                 ],
-                 stdout=PIPE,