logrotate: prepend extraConfig instead of postpending it

logrotate global options only affect rules following them - as such,
services.logrotate.extraConfig being added last makes the option only
useful for adding new paths but not for setting global options (e.g.
'dateext' so all logs are rotate with a date suffix).

Moving this first solves this problem, and we can then use this instead
of default paths config to append missingok/notifempty.

nixos/modules/services/logging/logrotate.nix

@@ -84,10 +84,6 @@ let
     };
 
     config.name = name;
-    config.extraConfig = ''
-      missingok
-      notifempty
-    '';
   };
 
   mkConf = pathOpts: ''
@@ -101,7 +97,11 @@ let
   '';
 
   paths = sortProperties (attrValues (filterAttrs (_: pathOpts: pathOpts.enable) cfg.paths));
-  configFile = pkgs.writeText "logrotate.conf" (concatStringsSep "\n" ((map mkConf paths) ++ [ cfg.extraConfig ]));
+  configFile = pkgs.writeText "logrotate.conf" (
+    concatStringsSep "\n" (
+      [ "missingok" "notifempty" cfg.extraConfig ] ++ (map mkConf paths)
+    )
+  );
 
 in
 {