Check for terminated processes properly

tests/applications/gnome-initial-setup/aaa_setup.pm

@@ -15,9 +15,11 @@ sub run {
 
     # Remove the user clear the system and force the gnome-initial-setup
     # to start on new boot.
-    assert_script_run("loginctl kill-user $username");
-    # that might switch us back to GDM, switch away if so
+    assert_script_run("loginctl kill-user $username", timeout => 120);
+    # closing the user might switch us back to GDM, let's go back there
     $self->root_console(tty => 3) if (check_screen 'graphical_login', timeout => 30);
+    # repeat checking that all processes are terminated, then proceed to delete the user
+    assert_script_run("for i in {1..30}; do ! pgrep -u $username >/dev/null && exit 0; sleep 1; done; pgrep -au $username; exit 1");
     assert_script_run("userdel -r $username");
 
     # Reboot the system to trigger GNOME initial setup