Remove the useless nova_ssh configure in the passwords.yml
Remove the useless nova_ssh configure in the passwords.yml

The nova_ssh_private_key and nova_ssh_public_key is useless, and
they should not be merged.

Change-Id: I7e7178398242060a78fe7caee6e14fa77f2ffe35
Closes-Bug: #1576199
(cherry picked from commit 9318b93c73355e2c58a9f0ac5fff0a17c7aaa0f0)

negronjl/kolla,negronjl/kolla,negronjl/kolla