Replace leftover usages of gtk_main_iteration(), which should not be
used since move away from gtk_main() in commit 21c3e2346b .
Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2773
Replace leftover usages of gtk_main_iteration(), which should not be
used since move away from gtk_main() in commit 21c3e2346b .
Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2773