Utils: Remove no longer used QtcProcess::start(QString, ...) overload

Change-Id: If74b1247c6c6afccfc04cff8915a9b759c8bfcaa
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/libs/utils/qtcprocess.h

@@ -105,7 +105,6 @@ public:
     void setDisableUnixTerminal();
 
     void start();
-    void start(const QString &cmd, const QStringList &args = {});
     void terminate();
     void interrupt();