nixos-module: do explicit postgres init

nixos-module.nix

@@ -151,15 +151,10 @@ in
     };
     services.postgresql = {
       enable = true;
-      ensureDatabases = [ "caveman" ];
-      ensureUsers = [ {
-        name = dbUser;
-        ensurePermissions = {
-          "DATABASE caveman" = "ALL PRIVILEGES";
-        };
-      } ];
       initialScript = pkgs.writeScript "initScript" ''
-        ALTER USER ${dbUser} WITH PASSWORD '${dbPassword}';
+        CREATE ROLE ${dbUser} LOGIN PASSWORD '${dbPassword}';
+        CREATE DATABASE caveman TEMPLATE template0 ENCODING UTF8;
+        GRANT ALL PRIVILEGES ON DATABASE caveman TO ${dbUser};
       '';
     };