Azure v1.2 Manifests: Fix namespaces for Knative and KFServing

[berndverst]

Which issue is resolved by this Pull Request:
Resolves kubeflow/kubeflow#5452

Description of your changes:
Moves KFServing and Knative into KFDef to support deployment to appropriate namespaces instead of the default Kubeflow namespace.

Checklist:

• Unit tests have been rebuilt:
  1. cd manifests/tests
  2. make generate-changed-only
  3. make test

[PatrickXYS]

/lgtm
/approve

I would encourage you find 2nd reviewer of Azure changes if possible @berndverst

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: berndverst, PatrickXYS

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• kfdef/OWNERS [PatrickXYS]
• stacks/azure/OWNERS [PatrickXYS,berndverst]
• tests/OWNERS [PatrickXYS]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[berndverst]

Thanks @PatrickXYS!