TD: remove unused clearLineSets()

d2ce7f8145 ("TD: Remove calls to now-empty clearLineSets() method")
removed last calls to clearLineSets(), so remove it entirely.

src/Mod/TechDraw/Gui/QGIFace.cpp

@@ -228,12 +228,6 @@ void QGIFace::setOutline(const QPainterPath & path)
     setPath(path);
 }
 
-/// remove the PAT hatch lines
-void QGIFace::clearLineSets()
-{
-    return;
-}
-
 /// add PAT hatch line set
 void QGIFace::addLineSet(LineSet& ls)
 {

src/Mod/TechDraw/Gui/QGIFace.h

@@ -108,7 +108,6 @@ public:
     //PAT fill parms & methods
     void setLineWeight(double weight);
 
-    [[deprecated]] void clearLineSets();
     void addLineSet(TechDraw::LineSet& ls);
 
     void lineSetToFillItems(TechDraw::LineSet& ls);