Summary Multi Plot: Minor adjustments (#8856)

Remove obsolete single summary template code
Always use maximized state of the QMdiSubWindow when a plot or view is deleted.
Move time axis to top
Set correct text for unused axis
Avoid assert when layout is requested for non existing legend

ApplicationLibCode/ProjectDataModel/RimPlotAxisProperties.h

@@ -61,6 +61,7 @@ public:
 
     void                  setEnableTitleTextSettings( bool enable );
     void                  enableRangeSettings( bool enable );
+    void                  setNameForUnusedAxis();
     void                  setNameAndAxis( const QString& name, RiaDefines::PlotAxis axis, int axisIndex = 0 );
     AxisTitlePositionType titlePosition() const override;