LOG error config for sysinv_api_workers

[junboli]

When we did not config sysinv_api_workers, or it is config incorrect, in this case, the sysinv api will not start due to there is no valid default value.

[Ghada Khalil (gkhalil)]

Please use the starlingx bug template. You can see it in launchpad when you report a new bug.
There is not enough information here to determine what the system impact is.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/668356
Committed: https://git.openstack.org/cgit/starlingx/config/commit/?id=c38efebf91a87c3c102fc71a9eef8fc35298aa23
Submitter: Zuul
Branch: master

commit c38efebf91a87c3c102fc71a9eef8fc35298aa23
Author: junboli <email address hidden>
Date: Tue Jul 9 02:24:33 2019 -0400

    Reraise exception and log error message

    When the sysinv_api_workers is configured incorrect, the
    sysinv api will not start due to the invalid default value.
    therefore will cause host swact.

    In this case, we can hardly figure out why that node is
    failure, This patch is to catch exception and log error
    message and then reraise exception if sysinv_api_workers
    is invalid value.

    Closes-bug: #1835142
    Change-Id: Ie8dd185a6a24aec28c8834d5013cc003a1f7792f
    Signed-off-by: junboli <email address hidden>