Remove extra SyncLibraries() call.

I imagine this was inserted to ensure the selected item is visible,
but selecting the item does that.  SyncLibraries() rebuilds the
entire tree, causing it to lose the user's scroll position.

Fixes https://gitlab.com/kicad/code/kicad/issues/4020

eeschema/libedit/lib_edit_frame.cpp

@@ -495,7 +495,6 @@ void LIB_EDIT_FRAME::SetCurPart( LIB_PART* aPart )
 
     m_toolManager->ResetTools( TOOL_BASE::MODEL_RELOAD );
     RebuildView();
-    SyncLibraries( false );
 }