Step 4: Consolidate manifests with multiple versions into 1

[yanniszark]

Umbrella Issue: #1735

Some manifests (e.g., notebooks controller, katib) have multiple versions. Take
the example of notebook-controller:

There are the following versions of manifests:

• The ones living in the upstream repo, used in development and testing.
• The base and overlays folders, in kubeflow/manifests. These were
  optimized to work with kfctl's kustomization combination magic.
• The base_v3 folder, designed to eschew vars and be buildable with
  kustomize. It imports files from base.

Consolidate multiple manifests versions into one.

[yanniszark]

Here is a matrix with the remaining work:

App	PR	Merged
PodDefaults	kubeflow/kubeflow#5719	✔️
Jupyter Web App	kubeflow/kubeflow#5721	✔️
CentralDashboard	kubeflow/kubeflow#5720	✔️
Profiles + KFAM	kubeflow/kubeflow#5718	✔️
Notebook Controller	kubeflow/kubeflow#5723	✔️
TF-Operator	kubeflow/training-operator#1255 kubeflow/training-operator#1259	✔️
PyTorch-Operator	kubeflow/pytorch-operator#323	✔️
MXNet Operator	kubeflow/mxnet-operator#91	✔️
MPI Operator	kubeflow/mpi-operator#340	✔️
XGBoost Operator	kubeflow/xgboost-operator#114	✔️

[yanniszark]

Closing as all manifests were consolidated.
/close