opendatahub folder have

• quickstart
• docs
• manifests/scripts to support fvt

After transition manifests are merged, the way to deploy modelmesh-serving is changed so we should update all related one.

The main goal of this update is to move away from kfdef to kustomize.

On modelmesh-serving/opendatahub:

• manifests and kfdef can be removed  
• scripts/gen-manifests: not used anymore, can be removed as well
• g*.sh scripts are deprecated, can be removed. 

On Makefile, needs to be updated:

• deploy-fvt-for-odh
• deploy-mm-for-odh

fast -> main branch

incubation/stable: are the same, release branch.

Make goals  deploy/install are not supported, thus, for now, need to continue using scripts.

NOTE: This task is migrated from GitHub to Jira. See previous discussion on GH.