pam: debian: Explicitly include pam_limits for xrdp sessions

This is required, as on Debian, pam_limits is not automatically included
for common sessions, and only for "login" sessions and session managers.
So, xrdp has to include it explicitly to make limits take effect.

See https://wiki.debian.org/Limits for details.

(cherry picked from commit f581d8e)

instfiles/pam.d/xrdp-sesman.debian

@@ -9,6 +9,8 @@ auth     required  pam_env.so readenv=1 envfile=/etc/default/locale
 
 @include common-password
 
+# Ensure resource limits are applied
+session    required     pam_limits.so
 @include common-session
 -session optional  pam_gnome_keyring.so auto_start
 -session optional  pam_kwallet5.so auto_start