eflowRec: replace Decorator with WriteDecorHandle

Hello,

This MR is replacing a Decorator with a WriteDecorHandle(+Key). The main motivation is to suppress these warnings which appear once per event in the HLT:

02:41:36 copyAuxStoreThinned                                    8     0 WARNING AthContainers/src/copyAuxStoreThinned.cxx:134: unlocked decoration passPFTrackPresel (269) in object of type xAOD::TrackParticleAuxContainer_v5

Cheers, Bertrand

Reconstruction/eflowRec/src/PFTrackPreselAlg.cxx

 /*
-  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "PFTrackPreselAlg.h"
 #include "StoreGate/ReadHandle.h"
 #include "StoreGate/WriteHandle.h"
+#include "StoreGate/WriteDecorHandle.h"
 #include "AthContainers/ConstDataVector.h"
 #include <memory>
 
-namespace {
-  const SG::AuxElement::Decorator<char> decPass("passPFTrackPresel");
-}
-
 PFTrackPreselAlg::PFTrackPreselAlg(const std::string& name, ISvcLocator* pSvcLocator)
   : AthReentrantAlgorithm(name, pSvcLocator)
 {
@@ -23,7 +20,12 @@ StatusCode PFTrackPreselAlg::initialize()
 {
   ATH_CHECK( m_inputTracksKey.initialize() );
   ATH_CHECK( m_outputTracksKey.initialize() );
+
+  m_outputDecorKey = m_inputTracksKey.key()+"."+m_outputDecorKey.key();
+  ATH_CHECK( m_outputDecorKey.initialize() );
+
   ATH_CHECK( m_trackSelTool.retrieve() );
+
   return StatusCode::SUCCESS;
 }
 
@@ -35,6 +37,9 @@ StatusCode PFTrackPreselAlg::execute(const EventContext &ctx) const
     ATH_MSG_ERROR("Failed to retrieve " << m_inputTracksKey);
     return StatusCode::FAILURE;
   }
+
+  SG::WriteDecorHandle<xAOD::TrackParticleContainer, char> decPass(m_outputDecorKey, ctx);
+
   auto output = std::make_unique<ConstDataVector<xAOD::TrackParticleContainer>>(SG::VIEW_ELEMENTS);
   for (const xAOD::TrackParticle* itrk : *input)
   {
@@ -48,5 +53,6 @@ StatusCode PFTrackPreselAlg::execute(const EventContext &ctx) const
   }
   auto outputHandle = SG::makeHandle(m_outputTracksKey, ctx);
   ATH_CHECK(outputHandle.put(std::move(output)) != nullptr);
+
   return StatusCode::SUCCESS;
 }