Add SM logging when a controller is not able to go-enabled

[Bin Qian]

Brief Description
-----------------
SM does not provide detail logging on which condition causes a controller is not being able to go-enabled. Adding a piece of log so to help troubleshooting.

Severity
--------
Minor: This change does not affect any functionality or user experience

Steps to Reproduce
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Provision a controller (e.g, simplex), ensure failure of a go-enabled test. The node will be disabled. However /var/log/sm.log does not provide indication of the reason why the node is disabled.

Expected Behavior
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It will be nice (for a designer) to see a log giving the indication why the node has failed/not go-enabled. This may be helpful when a log analysis is required (i.e, a lab is not directly accessible).

Actual Behavior
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As described, there isn't any logging info for that.

Reproducibility
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Always reproducible.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/664601

[Ghada Khalil (gkhalil)]

Low priority; would be nice to help with debugging, but does not gate any stx release

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/664601
Committed: https://git.openstack.org/cgit/starlingx/ha/commit/?id=3669405b628fdf0f8375f885eb962fb7f5f4c4f9
Submitter: Zuul
Branch: master

commit 3669405b628fdf0f8375f885eb962fb7f5f4c4f9
Author: Bin Qian <email address hidden>
Date: Mon Jun 10 16:15:32 2019 -0400

    Adding node disabled log info

    Add logging message to sm.log to indicate the reason why a controller
    cannot successfully go-enabled.

    Closes-Bug: 1832264
    Change-Id: I15a453b06869a157aecc6ba487889f9ae7d56e0b
    Signed-off-by: Bin Qian <email address hidden>