Respect AutoLoadP15Certs setting again when reading PKCS#15 cards

The new card keys view always reads S/MIME certificates from inserted
smart cards. Previously, this could be disabled for PKCS#15 cards. This
change restores this behavior.

(cherry picked from commit aa23dafc8c3dfa28d31beac6cc5c3773f00a71d6)

• GnuPG-bug-id: T7018