tests: Use gtk_tree_view_wait_for_draw() in treeview-scrolling
tests: Use gtk_tree_view_wait_for_draw() in treeview-scrolling

Replace all idle handlers waiting for draw and all manual runs of the
event loop with a call to gtk_tree_view_wait_for_draw().

ahodesuka/gtk,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita,msteinert/gtk,bratsche/gtk-,Distrotech/gtk2,Sidnioulz/SandboxGtk,alexlarsson/gtk,Adamovskiy/gtk,chergert/gtk,davidgumberg/gtk,Distrotech/gtk2,jigpu/gtk,Adamovskiy/gtk,alexlarsson/gtk,msteinert/gtk,msteinert/gtk,grubersjoe/adwaita,jadahl/gtk,Sidnioulz/SandboxGtk,msteinert/gtk,jigpu/gtk,jigpu/gtk,Adamovskiy/gtk,ahodesuka/gtk,jessevdk/gtk,Lyude/gtk-,ahodesuka/gtk,grubersjoe/adwaita,msteinert/gtk,davidgumberg/gtk,Distrotech/gtk2,jessevdk/gtk,jadahl/gtk,jadahl/gtk,jessevdk/gtk,alexlarsson/gtk,Lyude/gtk-,ebassi/gtk,ahodesuka/gtk,davidgumberg/gtk,jessevdk/gtk,Sidnioulz/SandboxGtk,bratsche/gtk-,jigpu/gtk,Lyude/gtk-,davidgumberg/gtk,ebassi/gtk,ebassi/gtk,chergert/gtk,Sidnioulz/SandboxGtk,alexlarsson/gtk,msteinert/gtk,Adamovskiy/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,grubersjoe/adwaita,jessevdk/gtk,jigpu/gtk,chergert/gtk,Adamovskiy/gtk,jigpu/gtk,jadahl/gtk,ahodesuka/gtk,Lyude/gtk-,jadahl/gtk,jadahl/gtk,jessevdk/gtk,jadahl/gtk,ahodesuka/gtk,Adamovskiy/gtk,alexlarsson/gtk,Lyude/gtk-,jadahl/gtk,ebassi/gtk,bratsche/gtk-,bratsche/gtk-,jigpu/gtk,ahodesuka/gtk,chergert/gtk,chergert/gtk,bratsche/gtk-,grubersjoe/adwaita,ahodesuka/gtk,ebassi/gtk,chergert/gtk,Distrotech/gtk2,Lyude/gtk-,davidgumberg/gtk,chergert/gtk,jessevdk/gtk,davidgumberg/gtk,bratsche/gtk-,Adamovskiy/gtk,Sidnioulz/SandboxGtk,Distrotech/gtk2,ebassi/gtk,Distrotech/gtk2,alexlarsson/gtk,Lyude/gtk-,grubersjoe/adwaita,grubersjoe/adwaita,davidgumberg/gtk,davidgumberg/gtk,chergert/gtk,Adamovskiy/gtk,jigpu/gtk,alexlarsson/gtk