[Futurev4] Remove ->Geant4/<- prefix in all the headers coming from Geant4 with new cmake

This follows the changes introduced in !807 (merged) and !824 (merged), this time addressing the Futurev4 branch. The Gaussino equivalent of this MR is Gaussino/Gaussino!54 (merged)

Example/LHCbLumi/src/AddLumiDetectorTool.cpp

@@ -16,8 +16,8 @@
  */
 
 #include "AddLumiDetectorTool.h"
-#include "Geant4/G4LogicalVolumeStore.hh"
-#include "Geant4/G4Trap.hh"
+#include "G4LogicalVolumeStore.hh"
+#include "G4Trap.hh"
 
 #include "LumiVolumeStructures.h"