fix: memory leak in CalorimeterClusterRecoCoG (#974)

### Briefly, what does this PR introduce?
A memory leak was caused by creating a new pointer `cl`, then push_back
`*cl`, but not deleting the pointer. This modifies the algorithm to use
objects instead of pointers. RVO and podio object encapsulation should
ensure performance is not affected.

Leak sanitizer output resolved:
```
Direct leak of 108512 byte(s) in 13564 object(s) allocated from:
    #0 0x55cbc7e9fded in operator new(unsigned long) (/home/wdconinc/git/EICrecon/.worktree/main/bin/eicrecon+0xeaded) (BuildId: 4702f11c9afe7b8bff422367fb6901ebdee7ea40)
    #1 0x7f92f7afe251 in eicrecon::CalorimeterClusterRecoCoG::reconstruct(edm4eic::ProtoCluster const&) const /home/wdconinc/git/EICrecon/.worktree/main/src/algorithms/calorimetry/CalorimeterClusterRecoCoG.cc:293:10
    #2 0x7f92f7af9dc9 in eicrecon::CalorimeterClusterRecoCoG::process(edm4eic::ProtoClusterCollection const*, edm4hep::SimCalorimeterHitCollection const*) /home/wdconinc/git/EICrecon/.worktree/main/src/algorithms/calorimetry/CalorimeterClusterRecoCoG.cc:55:18
    #3 0x7f92f7cb9713 in eicrecon::CalorimeterClusterRecoCoG_factoryT::Process(std::shared_ptr<JEvent const> const&) /home/wdconinc/git/EICrecon/.worktree/main/src/factories/calorimetry/CalorimeterClusterRecoCoG_factoryT.h:73:48
    #4 0x7f92f7cc0e54 in JMultifactoryHelperPodio<edm4eic::MCRecoClusterParticleAssociation>::Process(std::shared_ptr<JEvent const> const&) /opt/software/linux-debian12-x86_64_v2/gcc-12.2.0/jana2-2.1.1-txdpt66ozlvvdquuovpy44emsmsnuip4/include/JANA/JMultifactory.h:228:20
    #5 0x7f92ffc7ccf7 in JFactory::Create(std::shared_ptr<JEvent const> const&) (/usr/._local/jhttvx4bcm3wdo7jmamfg6pazkythsai/lib/libJANA.so+0x59cf7) (BuildId: e11aaf0447ef572861e6577e3cfce0750b7aa2c3)

Direct leak of 45664 byte(s) in 5708 object(s) allocated from:
    #0 0x55cbc7e9fded in operator new(unsigned long) (/home/wdconinc/git/EICrecon/.worktree/main/bin/eicrecon+0xeaded) (BuildId: 4702f11c9afe7b8bff422367fb6901ebdee7ea40)
    #1 0x7f92f7afe251 in eicrecon::CalorimeterClusterRecoCoG::reconstruct(edm4eic::ProtoCluster const&) const /home/wdconinc/git/EICrecon/.worktree/main/src/algorithms/calorimetry/CalorimeterClusterRecoCoG.cc:293:10
    #2 0x7f92f7af9dc9 in eicrecon::CalorimeterClusterRecoCoG::process(edm4eic::ProtoClusterCollection const*, edm4hep::SimCalorimeterHitCollection const*) /home/wdconinc/git/EICrecon/.worktree/main/src/algorithms/calorimetry/CalorimeterClusterRecoCoG.cc:55:18
    #3 0x7f92f7cb9713 in eicrecon::CalorimeterClusterRecoCoG_factoryT::Process(std::shared_ptr<JEvent const> const&) /home/wdconinc/git/EICrecon/.worktree/main/src/factories/calorimetry/CalorimeterClusterRecoCoG_factoryT.h:73:48
    #4 0x7f92f7cbac34 in JMultifactoryHelperPodio<edm4eic::Cluster>::Process(std::shared_ptr<JEvent const> const&) /opt/software/linux-debian12-x86_64_v2/gcc-12.2.0/jana2-2.1.1-txdpt66ozlvvdquuovpy44emsmsnuip4/include/JANA/JMultifactory.h:228:20
    #5 0x7f92ffc7ccf7 in JFactory::Create(std::shared_ptr<JEvent const> const&) (/usr/._local/jhttvx4bcm3wdo7jmamfg6pazkythsai/lib/libJANA.so+0x59cf7) (BuildId: e11aaf0447ef572861e6577e3cfce0750b7aa2c3)
```

### What kind of change does this PR introduce?
- [x] Bug fix (issue #__)
- [ ] New feature (issue #__)
- [ ] Documentation update
- [ ] Other: __

### Please check if this PR fulfills the following:
- [ ] Tests for the changes have been added
- [ ] Documentation has been added / updated
- [ ] Changes have been communicated to collaborators

### Does this PR introduce breaking changes? What changes might users
need to make to their code?
No.

### Does this PR change default behavior?
No.

Co-authored-by: Dmitry Kalinkin <[email protected]>

src/algorithms/calorimetry/CalorimeterClusterRecoCoG.cc

@@ -52,13 +52,16 @@ namespace eicrecon {
     auto associations = std::make_unique<edm4eic::MCRecoClusterParticleAssociationCollection>();
 
     for (const auto& pcl : *proto) {
-      auto *cl = reconstruct(pcl);
 
-      // skip null clusters
-      if (cl == nullptr) continue;
+      // skip protoclusters with no hits
+      if (pcl.hits_size() == 0) {
+        continue;
+      }
+
+      auto cl = reconstruct(pcl);
 
-      m_log->debug("{} hits: {} GeV, ({}, {}, {})", cl->getNhits(), cl->getEnergy() / dd4hep::GeV, cl->getPosition().x / dd4hep::mm, cl->getPosition().y / dd4hep::mm, cl->getPosition().z / dd4hep::mm);
-      clusters->push_back(*cl);
+      m_log->debug("{} hits: {} GeV, ({}, {}, {})", cl.getNhits(), cl.getEnergy() / dd4hep::GeV, cl.getPosition().x / dd4hep::mm, cl.getPosition().y / dd4hep::mm, cl.getPosition().z / dd4hep::mm);
+      clusters->push_back(cl);
 
       // If mcHits are available, associate cluster with MCParticle
       // 1. find proto-cluster hit with largest energy deposition
@@ -124,10 +127,10 @@ namespace eicrecon {
 
         // set association
         auto clusterassoc = associations->create();
-        clusterassoc.setRecID(cl->getObjectID().index); // if not using collection, this is always set to -1
+        clusterassoc.setRecID(cl.getObjectID().index); // if not using collection, this is always set to -1
         clusterassoc.setSimID(mcp.getObjectID().index);
         clusterassoc.setWeight(1.0);
-        clusterassoc.setRec(*cl);
+        clusterassoc.setRec(cl);
         clusterassoc.setSim(mcp);
       } else {
         m_log->debug("No mcHitCollection was provided, so no truth association will be performed.");
@@ -138,15 +141,15 @@ namespace eicrecon {
 }
 
 //------------------------------------------------------------------------
-edm4eic::Cluster* CalorimeterClusterRecoCoG::reconstruct(const edm4eic::ProtoCluster& pcl) const {
+edm4eic::Cluster CalorimeterClusterRecoCoG::reconstruct(const edm4eic::ProtoCluster& pcl) const {
   edm4eic::MutableCluster cl;
   cl.setNhits(pcl.hits_size());
 
   m_log->debug("hit size = {}", pcl.hits_size());
 
   // no hits
   if (pcl.hits_size() == 0) {
-    return nullptr;
+    return cl;
   }
 
   // calculate total energy, find the cell with the maximum energy deposit
@@ -290,7 +293,7 @@ edm4eic::Cluster* CalorimeterClusterRecoCoG::reconstruct(const edm4eic::ProtoClu
   cl.addToShapeParameters( eigenValues_3D[1].real() ); // 3D x-y-z cluster width 2
   cl.addToShapeParameters( eigenValues_3D[2].real() ); // 3D x-y-z cluster width 3
 
-  return new edm4eic::Cluster(cl);
+  return std::move(cl);
 }
 
 } // eicrecon

src/algorithms/calorimetry/CalorimeterClusterRecoCoG.h

@@ -58,7 +58,7 @@ namespace eicrecon {
 
   private:
 
-    edm4eic::Cluster* reconstruct(const edm4eic::ProtoCluster& pcl) const;
+    edm4eic::Cluster reconstruct(const edm4eic::ProtoCluster& pcl) const;
 
   };