d/patches: prefer x-terminal-emulator
GNOME and glib currently do not provide any mechanism for setting a given terminal emulator as the default one. Since Debian has its own way of dealing with this specific problem, via the alternatives system, this patch makes glib use x-terminal-emulator instead of its hardcoded defaults, while keeping the pre-existing list as a fallback in case x-terminal-emulator is unavailable for some reason.
This solution has been recommended by upstream in the past, see https://gitlab.gnome.org/GNOME/glib/-/issues/338#note_205945
Closes: #773915