Various plugins: Remove unused variables

Change-Id: Ie2e5eb38d81a7582c5715654f09f28deb4ab11c5
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/cppeditor/doxygengenerator.cpp

@@ -28,8 +28,6 @@ QString DoxygenGenerator::generate(QTextCursor cursor,
                                    const CPlusPlus::Snapshot &snapshot,
                                    const Utils::FilePath &documentFilePath)
 {
-    const QTextCursor initialCursor = cursor;
-
     const QChar &c = cursor.document()->characterAt(cursor.position());
     if (!c.isLetter() && c != QLatin1Char('_') && c != QLatin1Char('['))
         return QString();