ssh key deletion in instance deletion fails with openstack driver in salt-cloud

Description of Issue/Question

When deleting an instance with salt-cloud -d with openstack driver, ssh key removal fail and I get an error message sayng [ERROR ] There was an error destroying machines: 'dict' object has no attribute 'public_ips'

There are two problems in this line

https://github.com/saltstack/salt/blob/b2258397cb9018530cf2acba28447a047151fbc5/salt/cloud/clouds/openstack.py#L809

First, node is a dict, not an object, so getattr(node, ...) should be replaced by node.get(...). We are looking for a key, not an attribute.

Secondly, ssh_interface is not a first level member of __opts__ but appears deeper in the structure, either in provider, profile or instance level, so __opts__.get('ssh_interface', 'public_ips') always returns public_ips regardless of what you have configured as ssh_interface.

Setup

salt-cloud 2019.2 from official repo on Debian 9 stretch

Steps to Reproduce Issue

• Configure salt-cloud with openstack driver and ssh_interface: private_ips
• Destroy an instance
• Look at the error message (first problem) and see it still look for public_ips (second problem)

Versions Report

# salt -V
Salt Version:
           Salt: 2019.2.0
 
Dependency Versions:
           cffi: 1.12.3
       cherrypy: Not Installed
       dateutil: 2.5.3
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.9.4
        libgit2: 0.24.5
        libnacl: Not Installed
       M2Crypto: 0.24.0
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.4.8
   mysql-python: Not Installed
      pycparser: 2.19
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: 0.24.2
         Python: 2.7.13 (default, Sep 26 2018, 18:42:22)
   python-gnupg: Not Installed
         PyYAML: 3.12
          PyZMQ: 16.0.2
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.4.3
            ZMQ: 4.2.1
 
System Versions:
           dist: debian 9.9 
         locale: UTF-8
        machine: x86_64
        release: 4.9.0-8-amd64
         system: Linux
        version: debian 9.9 

Start at salt/cloud/clouds/openstack.py line 809 and inspect how the node data and ssh_interface configuration are read during salt-cloud -d. Reproduce with an OpenStack profile using ssh_interface: private_ips, then verify instance deletion removes the SSH key without the public_ips error and respects the configured interface.