refactor: clean up verbose migration comments

Remove redundant Qt6 migration comments that restate obvious API changes:
- QtConcurrent::run parameter order explanations (preserved where lambda wrapping needed)
- QStringRef/QStringView API changes (shortened to essential info)
- QComboBox::activated signal signature change
- QMap::unite() removal semantics
- QAction include path change
- QMouseEvent/QWheelEvent position() API
- QList/QVector equivalence in Qt6
- QFuture continuation API
- Code generation comments

Preserved comments explaining non-obvious Qt6 behavior or necessary
API migration details.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/Lts/Viewer/SituationMap/GraphicalObjects/graphical_object_renderer_attributes.cpp

@@ -103,7 +103,7 @@ bool GraphicalObjectRendererAttributes::updateViewImpl()
     if (m_logger.isDebugEnabled())
       qCritical() <<  " debugInfo='" << m_debugInfo << "'" << ", QVariantMap before unite " << cur;
 
-    // Qt6: QMap::unite() removed; insert only the keys not already present (unite semantics).
+    // Insert only missing keys (QMap::unite() removed in Qt6)
     const QVariantMap otherAttrs = m_attributeMap.value();
     for (auto it = otherAttrs.constBegin(); it != otherAttrs.constEnd(); ++it)
       if (!cur.contains(it.key()))