Debugger: Move some code around

Parts of the Debugger engine rampdown mechanisms are
essentially one code path now, don't distribute that
over four classes.

Change-Id: I4c6edbc0db94d1f658b0c1d9c154552f286db876
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/debuggerruncontrol.h

@@ -58,13 +58,10 @@ public:
     void start() override;
     void stop() override;
 
-    void startFailed();
-
     void notifyInferiorIll();
     Q_SLOT void notifyInferiorExited(); // Called from Android.
     void quitDebugger();
     void abortDebugger();
-    void debuggingFinished();
 
     const Internal::DebuggerRunParameters &runParameters() const;