expander-row: Prevent gtk_widget_show_all()

Set no-show-all to true to prevent gtk_widget_show_all() from breaking
the internal state.

Fixes Librem5/libhandy#257
12 jobs for expander-row-no-show-all in 14 minutes and 22 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #264207
librem5
api-visibility

00:02:40

passed #264209
librem5
build-debian-clang

00:04:03

passed #264208
librem5
build-debian-gcc

00:03:01

passed #264210
librem5
build-fedora-gcc

00:03:44

 
  Test+Docs
passed #264211
librem5
build-gtkdoc

00:02:11

passed #264212
librem5
unit-test

00:02:07

43.8%
 
  Package
passed #264213
librem5
package-debian-buster

00:02:02

passed #264214
librem5:arm64
package-debian-buster:arm64

00:06:07

passed #264215
flatpak
package-flatpak

00:01:11

passed #264216
flatpak
package-flatpak-glade

00:02:56

 
  Test Package
passed #264217
librem5
autopkgtest-debian-buster-package

00:01:58

passed #264218
librem5
lintian-debian-buster-package

00:00:46