Fix unused placeholders in german 'is typing' translation

locale/de/LC_MESSAGES/converse.json

@@ -137,11 +137,11 @@
          ],
          "is typing": [
             null,
-            "%1$s tippt"
+            "tippt"
          ],
          "has stopped typing": [
             null,
-            "%1$s tippt nicht mehr"
+            "tippt nicht mehr"
          ],
          "has gone away": [
             null,

locale/de/LC_MESSAGES/converse.po

@@ -162,11 +162,11 @@ msgstr "Ich"
 
 #: converse.js:1158
 msgid "is typing"
-msgstr "%1$s tippt"
+msgstr "tippt"
 
 #: converse.js:1161
 msgid "has stopped typing"
-msgstr "%1$s tippt nicht mehr"
+msgstr "tippt nicht mehr"
 
 #: converse.js:1167 converse.js:1447
 msgid "has gone away"