treewide: drop usage of nixfmt-rfc-style alias

doc/languages-frameworks/python.section.md

···
 * `pythonImportsCheck` is set. This is still a good smoke test even if `pytestCheckHook` is set.
 * `meta.platforms` takes the default value in many cases.
   It does not need to be set explicitly unless the package requires a specific platform.
-* The file is formatted with `nixfmt-rfc-style`.
+* The file is formatted with `nixfmt`.
 * Commit names of Python libraries must reflect that they are Python
   libraries (e.g. `python313Packages.numpy: 1.11 -> 1.12` rather than `numpy: 1.11 -> 1.12`).
 * The current default version of python should be included

pkgs/applications/editors/vscode/extensions/README.md

···
 
 * When adding a new extension, place its definition in a `default.nix` file in a directory with the extension's ID (e.g. `publisher.extension-name/default.nix`) and refer to it in `./default.nix`, e.g. `publisher.extension-name = callPackage ./publisher.extension-name { };`.
 
-* Currently `nixfmt-rfc-style` formatter is being used to format the VSCode extensions.
+* Currently `nixfmt` formatter is being used to format the VSCode extensions.
 
 * Respect `alphabetical order` whenever adding extensions. On disorder, please, kindly open a PR re-establishing the order.
 

pkgs/by-name/gr/gren/update.sh

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 #!/usr/bin/env nix-shell
-#!nix-shell -i bash -p cabal2nix curl jq nix-update nixfmt-rfc-style
+#!nix-shell -i bash -p cabal2nix curl jq nix-update nixfmt
 
 set -euo pipefail
 

pkgs/by-name/ni/nixfmt-tree/package.nix

···
       You can achieve similar results by manually configuring `treefmt`:
       ```nix
       pkgs.treefmt.withConfig {
-        runtimeInputs = [ pkgs.nixfmt-rfc-style ];
+        runtimeInputs = [ pkgs.nixfmt ];
 
         settings = {
           # Log level for files treefmt won't format

pkgs/os-specific/linux/kernel/update-xanmod.sh

···
 #!/usr/bin/env nix-shell
-#!nix-shell -i bash -p bash nix-prefetch curl jq gawk gnused nixfmt-rfc-style
+#!nix-shell -i bash -p bash nix-prefetch curl jq gawk gnused nixfmt
 
 set -euo pipefail
 

pkgs/servers/x11/xorg/update.py

···
 #!/usr/bin/env nix-shell
-#!nix-shell --pure --keep NIX_PATH -i python3 -p nix git nixfmt-rfc-style "python3.withPackages (ps: [ ps. packaging ps.beautifulsoup4 ps.requests ])"
+#!nix-shell --pure --keep NIX_PATH -i python3 -p nix git nixfmt "python3.withPackages (ps: [ ps. packaging ps.beautifulsoup4 ps.requests ])"
 
 # Usage: Run ./update.py from the directory containing tarballs.list. The script checks for the
 # latest versions of all packages, updates the expressions if any update is found, and commits