factory: include pam_keyinit.so in PAM factory configuration

We use the keyring, so let's make sure it gets properly initialized for
sessions in factory reset mode.

(cherry picked from commit 4c92bf408db4f91928389c49bf06cfe5d7383d9a)
(cherry picked from commit a4fc3c88f122de263bd0a1bd6a86b6e557ee5531)
(cherry picked from commit cf1500b62036fd3f7399e8ce306c641d1623ffbc)

factory/etc/pam.d/system-auth

@@ -13,6 +13,7 @@ account  required   pam_permit.so
 password sufficient pam_unix.so nullok sha512 shadow try_first_pass try_authtok
 password required   pam_deny.so
 
+-session optional   pam_keyinit.so revoke
 -session optional   pam_loginuid.so
 -session optional   pam_elogind.so
 session  sufficient pam_unix.so