main/postmarketos-ui-phosh: remove xwayland, it is a phosh dependency

XWayland is a phosh dependency. Having it in pmb_recommends adds nothing and can be confusing, since power users would expect that removing it from world would remove the package. That will never be the case since phosh depends on it.

Draft waiting for upstream: https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/33460 Ready!