Fix helium HLT2 lines (option 2)

Switch the particle combiner from DecayTreeFitter to the default `ParticleVertexFitter and re-include helium lines.

This is intended to be a fix for #827 (closed).

Relies on Rec!4061 (merged)

Hlt/Hlt2Conf/python/Hlt2Conf/lines/ift/__init__.py

@@ -13,6 +13,7 @@ Submodule that defines all ift HLT2 and sprucing lines
 """
 
 from . import hlt2_ift_femtoscopy
+from . import hlt2_ift_pp_He
 from . import hlt2_ift_smog2
 from . import hlt2_ift_smog2_generic
 from . import hlt2_ift_smog2_charm
@@ -26,6 +27,7 @@ from . import hlt2_ift_smog2_CEP
 # provide "all_lines" for correct registration by the overall HLT2 lines module
 all_lines = {}
 all_lines.update(hlt2_ift_femtoscopy.all_lines)
+all_lines.update(hlt2_ift_pp_He.all_lines)
 all_lines.update(hlt2_ift_smog2.all_lines)
 all_lines.update(hlt2_ift_smog2_generic.all_lines)
 all_lines.update(hlt2_ift_smog2_charm.all_lines)
@@ -48,6 +50,7 @@ ift_full_lines.update(hlt2_ift_isolated_highpt_photon.all_lines)
 
 ift_turbo_lines = {}
 ift_turbo_lines.update(hlt2_ift_femtoscopy.all_lines)
+ift_turbo_lines.update(hlt2_ift_pp_He.all_lines)
 ift_turbo_lines.update(hlt2_ift_smog2_generic.turbo_lines)
 ift_turbo_lines.update(hlt2_ift_smog2_charm.turbo_lines)
 ift_turbo_lines.update(hlt2_ift_smog2_chargedPID.turbo_lines)