nix generator: less repetition

modules/services/immich/default.nix

@@ -19,13 +19,12 @@ let
     ];
     text = ''
       set -x
-      ${lib.concatLines (
-        map
+      ${lib.concatMapStringsSep "\n"
         (name: ''
           mkdir /data/${name}
           bindfs -u ${cfg.bindAsUser} /var/run/immich/bind-paths/${name} /data/${name}'')
         (lib.attrNames cfg.bindPaths)
-      )}
+      }
       exec setpriv \
         --ruid ${immich-user} \
         --inh-caps -sys_admin,-setuid,-setgid \