Replace GaussinoExtLibs with DD4hepDDG4 in lcg devX slots

Requires Gaussino/Gaussino!181 to be enabled for dev3 and dev4 slots

lhcbnightlyconf/Main.py

@@ -71,6 +71,9 @@ def create_head_slot(name,
     if hasattr(slot, 'GaussinoExtLibs'):
         slot.GaussinoExtLibs.checkout_opts['url'] = (
             'https://gitlab.cern.ch/Gaussino/gaussinoextlibs.git')
+    if hasattr(slot, 'DD4hepDDG4'):
+        slot.DD4hepDDG4.checkout_opts['url'] = (
+            'https://gitlab.cern.ch/Gaussino/DD4hepDDG4.git')
     for pname in PROJECTS_WITHOUT_TESTS:
         if hasattr(slot, pname):
             getattr(slot, pname).no_test = True