gtk4: fix font rendering with wayland fractional scaling and ngl/vulkan renderer
The new "unified GPU" renderer (See https://blog.gtk.org/2024/01/28/new-renderers-for-gtk/ for more information) which supports both Vulkan and OpenGL in GTK has additional support for the Wayland fractional scaling protocol.
The overrides that VTE is doing for fonts doesn't quite do enough in this case. So far, I've only encountered this on monitors with fractional scaling (this one in particular is 1.5x scale).
The problem appears to be that the hinting done after the ink rect is determined (to calculate pixel grid alignment) causes it to fall outside the expected ink rect in Cairo.
Some more information: