Revert "nixos/podman: use given package for dockerCompat"

This reverts commit df74ebcabb, which breaks
eval when Podman is enabled due to infinite recursion [0] [1].

I take full responsibility for merging this without looking too closely
nor running the NixOS test.

[0]: df74ebcabb (commitcomment-145003824)
[1]: https://github.com/NixOS/nixpkgs/pull/267321#issuecomment-2267076978

nixos/modules/virtualisation/podman/default.nix

@@ -5,7 +5,7 @@ let
 
   inherit (lib) mkOption types;
 
-  podmanPackage = (cfg.package.override {
+  podmanPackage = (pkgs.podman.override {
     extraPackages = cfg.extraPackages
       # setuid shadow
       ++ [ "/run/wrappers" ]