nixos/acme: fix incorrectly using mkRenamedOptionModule in submodule

Per https://github.com/NixOS/nixpkgs/issues/96006, this does not work as
expected.

The warning trace will be emitted regardless of whether the option is
set, rendering it pointless. It does not work at the top-level either
(i.e. as `"security" "acme" "defaults" "credentialsFile"`), As such,
remove it entirely.

nixos/modules/security/acme/default.nix

@@ -677,10 +677,6 @@ let
       };
     in
     {
-      imports = [
-        (lib.mkRenamedOptionModule [ "credentialsFile" ] [ "environmentFile" ])
-      ];
-
       options = {
         validMinDays = lib.mkOption {
           type = lib.types.nullOr lib.types.int;