Decouple lhcb-gaussino-fastsim

This is needed because we would d like to test Geant4 new cmake with lhcb-gaussino, but it won't work with all the developments related to fast simulation in Gaussino, and in particular, Geant4 10.7. Therefore, the lhcb-gaussino-fastsim label cannot be added in the same MRs as lhcb-gaussino.

I added also a commit that decouples fast simulation developments from Futurev4 by targeting a new branch FASTSIM for Gaussino & Gauss.

lhcbnightlyconf/Gauss.py

@@ -334,11 +334,22 @@ gaussinoFastSim = create_gaussino_slot(
     'lhcb-gaussino-fastsim',
     'Test build of Fast Simulation Interface in Gaussino and Gauss-on-Gaussino',
 )
-for project in gaussinoFastSim.activeProjects:
-    if project.name not in ['PARAM', 'DBASE', 'Gaussino', 'Gauss']:
-        project.checkout_opts['merges'] = ['all', 'label=lhcb-gaussino']
 gaussinoFastSim.cache_entries['GEANT4FILES_VERSION'] = 'v107r0'
 gaussinoFastSim.cache_entries['GEANT4_TAG'] = 'lhcb/v10.7.0-branch'
+gaussinoFastSim.Gaussino.version = 'FASTSIM'
+gaussinoFastSim.Gaussino.checkout_opts = {
+    'merges': [
+        # 'all', disabled on purpose
+        'label=lhcb-gaussino-fastsim',
+    ],
+}
+gaussinoFastSim.Gauss.version = 'FASTSIM'
+gaussinoFastSim.Gauss.checkout_opts = {
+    'merges': [
+        # 'all', disabled on purpose
+        'label=lhcb-gaussino-fastsim',
+    ],
+}
 slots.append(gaussinoFastSim)
 
 # Slot for Gaussino with the new CMake