nixosTests.nginx-variants: migrate to runTest

Part of #386873

nixos/tests/all-tests.nix

···
   nginx-status-page = runTest ./nginx-status-page.nix;
   nginx-tmpdir = runTest ./nginx-tmpdir.nix;
   nginx-unix-socket = runTest ./nginx-unix-socket.nix;
-  nginx-variants = handleTest ./nginx-variants.nix {};
+  nginx-variants = import ./nginx-variants.nix { inherit pkgs runTest; };
   nifi = runTestOn ["x86_64-linux"] ./web-apps/nifi.nix;
   nitter = handleTest ./nitter.nix {};
   nix-config = handleTest ./nix-config.nix {};

nixos/tests/nginx-variants.nix

···
-{
-  system ? builtins.currentSystem,
-  config ? { },
-  pkgs ? import ../.. { inherit system config; },
-}:
-
-with import ../lib/testing-python.nix { inherit system pkgs; };
-
+{ pkgs, runTest, ... }:
 builtins.listToAttrs (
   builtins.map
     (nginxPackage: {
       name = pkgs.lib.getName nginxPackage;
-      value = makeTest {
+      value = runTest {
         name = "nginx-variant-${pkgs.lib.getName nginxPackage}";
 
         nodes.machine =