Revert G4 MT for 10.7.3

lhcbnightlyconf/G4R10.py

@@ -60,7 +60,7 @@ g4dev.desc = 'Testing new Geant4 release for LHCb Simulation'
 g4dev.cache_entries = {
     'CMAKE_USE_CCACHE': True,
     'GAUDI_LEGACY_CMAKE_SUPPORT': True,
-    'GEANT4_BUILD_MULTITHREADED': True,
+    # 'GEANT4_BUILD_MULTITHREADED': True,
     # 'GEANT4_TAG': 'lhcb/v10.7.3-branch',
     # 'GEANT4FILES_VERSION': 'v107r1'
 }