GUACAMOLE-2181: Remove LDAP reference to non-existent overlay language.

The LDAP extension's guac-manifest.json refers to a German translation
in "de.json", but that translation file doesn't actually exist for LDAP,
hence the following warning at startup:

    WARN: Overlay language resource "de" does not exist.

This corrects that warning by removing the erroneous reference.

extensions/guacamole-auth-ldap/src/main/resources/guac-manifest.json

@@ -10,7 +10,6 @@
     ],
 
     "translations" : [
-        "translations/de.json",
         "translations/en.json",
         "translations/zh.json"
     ]