In 80ea989ac9 we updated to x-d-p-gtk 1.10.0, in which some portals were extracted to x-d-p-gnome and were disabled by default in x-d-p-gtk. This was continued with x-d-p-gtk 1.15 bump in 6d646062c8, which default-enabled all portals because of port to Meson’s auto features.
But I do not think the conflict between portal implementations from x-d-p-gtk and x-d-p-gnome has ever been an issue at runtime – since `gnome` comes before `gtk` alphabetically, the `gnome` portal should have been always preferred when both were available.
And since x-d-p 1.17.0, the portal implementation conflicts are a complete non-issue, as desktop environments can configure which implementation to use for each portal.
Since the benefits of disabling the extra portals are minimal and can lead to conflicts when multiple DEs are enable, we have stopped DEs from doing that in parent commits. This makes the argument unused so let’s remove it.
7f2a6f17fc