Clear field listener when quitting

Fixes https://gitlab.com/kicad/code/kicad/-/issues/18016

eeschema/schematic.cpp

@@ -120,6 +120,8 @@ SCHEMATIC::SCHEMATIC( PROJECT* aPrj ) :
 
 SCHEMATIC::~SCHEMATIC()
 {
+    PROPERTY_MANAGER::Instance().UnregisterListeners( TYPE_HASH( SCH_FIELD ) );
+
     delete m_currentSheet;
     delete m_connectionGraph;
 }

include/properties/property_mgr.h

@@ -277,6 +277,11 @@ public:
         m_listeners[aType].emplace_back( aListenerFunc );
     }
 
+    void UnregisterListeners( TYPE_ID aType )
+    {
+        m_listeners[aType].clear();
+    }
+
 private:
     PROPERTY_MANAGER() :
             m_dirty( false ),