[ironic] inspector auto-discovery disabled by default in bifrost

Hi Ironicers,

The Ironic team recently decided to change the default inspector auto-discovery behavior in bifrost. In the past, this feature was enabled by default. However, this was causing issues in deployments where the operators had no intention of using auto-discovery but the IPA somehow booted anyway, causing port conflicts and creating failure modes which were particularly tricky to debug. For this reason, inspector auto-discovery has been disabled by default with this change which merged yesterday:

https://review.opendev.org/c/openstack/bifrost/+/762998

This is to make sure that the operators utilising inspector auto-discovery in bifrost are aware of this change and can re-enable inspector discovery if desired.

Best regards, Jacob