display: Don't use gtk_widget_show_all

It is removed in GTK+ 4
11 jobs for no-no-show-all in 3 minutes and 35 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #123964
build

00:01:57

 
  Test
passed #123966
asan

00:01:36

passed #123965
test

00:00:46

 
  Manual
manual #123971
allowed to fail manual
armv8
manual #123967
allowed to fail manual
flatpak
manual #123970
allowed to fail manual
msan
manual #123972
allowed to fail manual
ppc64le
manual #123968
allowed to fail manual
tsan
manual #123969
allowed to fail manual
ubsan
 
  Review
manual #123973
allowed to fail manual
review
manual #123974
allowed to fail manual
stop_review