fixes #12801

get ssh_interface if it is set, otherwise just use public_ips
Merge pull request #12868 from gtmanfred/private_ips

fixes #12801
Delete cache when destroying minions

only if update_cachedir is set
add delete_minion_cachedir to destroy functions

Also to the missing_node_cache function to delete the cache on
list_nodes_full, if the server was deleted with something besides
salt-cloud.