Fix memory leak in MuPatTrackBuilder

Follow up of !37460 (merged), apparently I forgot one call-chain leading MuPatHitTool.

MuonSpectrometer/MuonReconstruction/MuonRecTools/MuonRecToolInterfaces/MuonRecToolInterfaces/IMuonTrackFinder.h

@@ -39,6 +39,8 @@ namespace Muon {
     */
     virtual TrackCollection* find( const std::vector<const MuonSegment*>& segments ) const = 0;
 
+    virtual void cleanUp() const = 0;
+
   };
   
   inline const InterfaceID& IMuonTrackFinder::interfaceID()