dbus service: use makeDBusConf

nixos/modules/services/system/dbus-session-local.conf.in

···
-<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
- "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
-<busconfig>
-  @extra@
-</busconfig>

nixos/modules/services/system/dbus-system-local.conf.in

···
-<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
- "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
-<busconfig>
-  <servicehelper>@servicehelper@</servicehelper>
-  @extra@
-</busconfig>

nixos/modules/services/system/dbus.nix

···
 
   homeDir = "/run/dbus";
 
-  systemExtraxml = concatStrings (flip concatMap cfg.packages (d: [
-    "<servicedir>${d}/share/dbus-1/system-services</servicedir>"
-    "<includedir>${d}/etc/dbus-1/system.d</includedir>"
-  ]));
-
-  sessionExtraxml = concatStrings (flip concatMap cfg.packages (d: [
-    "<servicedir>${d}/share/dbus-1/services</servicedir>"
-    "<includedir>${d}/etc/dbus-1/session.d</includedir>"
-  ]));
-
-  configDir = pkgs.runCommand "dbus-conf"
-    { preferLocalBuild = true;
-      allowSubstitutes = false;
-    }
-    ''
-      mkdir -p $out
-
-      sed '${./dbus-system-local.conf.in}' \
-        -e 's,@servicehelper@,${config.security.wrapperDir}/dbus-daemon-launch-helper,g' \
-        -e 's,@extra@,${systemExtraxml},' \
-        > "$out/system-local.conf"
-
-      sed '${./dbus-session-local.conf.in}' \
-        -e 's,@extra@,${sessionExtraxml},' \
-        > "$out/session-local.conf"
-    '';
+  configDir = pkgs.makeDBusConf {
+    suidHelper = "${config.security.wrapperDir}/dbus-daemon-launch-helper";
+    serviceDirectories = cfg.packages;
+  };
 
 in