pantheon.wingpanel-applications-menu: 2.4.2 -> 2.4.3

Now finally builds with Meson, where it was available
since last release but needed several fixes to be release quality
IMHO.

Also dropped xdg patch since because meson [0].

https://github.com/elementary/applications-menu/releases/tag/2.4.3

[0]: https://github.com/elementary/applications-menu/commit/58cd96a4cc5c98bbf379f119cd2e92d0142a80d9