Debugger: fix initial value of operate by instruction for cdb

Change-Id: Ifad9fdd96175a304130b8f41f53c235c0260220d
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/cdb/cdbengine.cpp

@@ -226,7 +226,7 @@ void CdbEngine::init()
     m_stopMode = NoStopRequested;
     m_nextCommandToken  = 0;
     m_currentBuiltinResponseToken = -1;
-    m_operateByInstruction = action(OperateByInstruction)->isChecked();
+    m_operateByInstruction = true; // Default CDB setting.
     m_hasDebuggee = false;
     m_sourceStepInto = false;
     m_watchPointX = m_watchPointY = 0;