[V2V] Have ConversionHost explicitly search authentications for auth type

[djberg96]

Within the ConversionHost model, because of the way the Authentications module was originally written, it's possible that the authentication_type('v2v') call won't actually pick up the properly authentication.

This adds a default where it will explicitly check for the auth_type if the first attempt doesn't find anything.

Fixes #18724

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1708739

[miq-bot]

Checked commits https://github.com/djberg96/manageiq/compare/b287b5ac3ac7638c6d3901b289dbb2b0dfcc9dee~...ea45831ca71f9053a6dbe9c39762d8795e1fc686 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
3 files checked, 0 offenses detected
Everything looks fine. 🍰

[djberg96]

@miq-bot add_label hammer/yes

[simaishi]

Hammer backport details:

$ git log -1
commit cec25e0a0c940b555921ce361dbdf8c1eb86a93d
Author: Adam Grare <[email protected]>
Date:   Sat May 11 17:48:52 2019 -0400

    Merge pull request #18748 from djberg96/conversion_host_ansible_playbook_default_credentials
    
    Have ConversionHost explicitly search authentications for auth type
    
    (cherry picked from commit 54bc9a86e5b4199d7b4a2f7587ca8aea9136a545)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1712135