Goal: 

• As a developer, I need to limit my usage of oslo.service and related configuration options. As a result, I need to move the configuration shutdown timeout option to Ironic.

Context:

• Oslo.service option - https://github.com/openstack/oslo.service/blob/master/oslo_service/_options.py#L60
• Ironic’s use - https://opendev.org/openstack/ironic/src/branch/master/ironic/conductor/rpc_service.py#L110
• Ironic is one of the few services which utilize this option, and it is actually more about the shutdown of the conductor service. The value is used as a timeout to govern how much longer the process should wait before forcing the exit of tasks.
• There is a distinct possibility that this may be forced, if oslo removes the option. The only other service which is a known consumer of this option is mistral.

A short path is to just port the option over and update it so it loads from Ironic’s default section. A possible risk is that the option registration may cause a conflict with the existing option (graceful_shutdown_timeout).

Acceptance Criteria:

• Ironic is no longer using the oslo.service provided graceful_shutdown_timeout option or supplies the option from ironic's configuration itself.