oslo_config provide a utility for generating sample config files,
which provide more detail about opts, like Minimum/Maximum value
and Allowed values.
So drop Ironic's "generate_sample.sh" which was copied from
oslo-incubator long time ago.
Add a new entry point "ironic" under oslo.config.opts namespace to
explore config options to oslo-config-generator.
After this patch, new config options of Ironic code should register
with ironic/conf/opts.py. New external libraries should
register with tools/config/ironic-config-generator.conf
There is a bug #1554657 with oslo-config about deprecated_group.
This bug have impact of some configs from keystonemiddleware
and oslo.messaging in ironic.conf.sample
So currently, deprecated option should always add the deprecated_group
even it didn't alter the group, otherwise the deprecated group value will
be 'DEFAULT'.
Update etc/ironic/ironic.conf.sample via running 'tox -egenconfig'.
Closes-Bug: #1564195
Change-Id: If7721e98e69b6f54f1ee04a07477396b86583371
773aa20a4a