RemoteLinux: Prevent step factory sharing by inheritance

This was the preferred way for a while, but has been superseded by
creating the steps by ID.

Not exposing the factory classes in a header prevents following
the old approach in downstream plugins.

Change-Id: Iaa89458a87602006f1a05fa142a34cc1f9d63c64
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/remotelinux/genericdeploystep.h

@@ -3,14 +3,8 @@
 
 #pragma once
 
-#include <projectexplorer/buildstep.h>
-
 namespace RemoteLinux::Internal {
 
-class GenericDeployStepFactory : public ProjectExplorer::BuildStepFactory
-{
-public:
-    GenericDeployStepFactory();
-};
+void setupGenericDeployStep();
 
 } // namespace RemoteLinux::Internal