ProjectExplorer: Remove RunConfiguration::canRunForNode()

All implementations that were returning true effectively did that
in case of node->buildKey() == rc->buildKey(), either directly or
in disguise of qmake's projectPath, so this is the check that is
used now in the two places where this is used.

The new global has the theoretical potential of return true in
cases where it did not before.

Change-Id: Ic5829de5fef0f9a04d516a3d9207685055823775
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/ios/iosrunconfiguration.h

@@ -57,7 +57,6 @@ private:
     friend class IosDeviceTypeAspect;
     void updateDisplayNames();
     void updateEnabledState() final;
-    bool canRunForNode(const ProjectExplorer::Node *node) const final;
 
     IosDeviceTypeAspect *m_deviceTypeAspect = nullptr;
 };