OSSM: Add SM overlays to notebook-controller manifests

[cam-garrison]

Description

This PR adds Service Mesh overlays to the two notebook controller manifests. This is needed as v2 operator pulls manifests from kubeflow:v1.7 branch rather than from odh-manifests as it previously did.

The overlays changes are very minimal - in kf-notebook-controller, the service mesh overlay patches the configmap to ensure USE_ISTIO=true, and that the default gateway is opendatahub/odh-gateway. In odh-notebook-controller, the only patch is to the image to use our latest maistra build - once PR #172 is merged, we can safely remove this overlay.

Since the changes in this PR are contained to service-mesh overlays, these changes should not interfere with non-service mesh deployments.

How Has This Been Tested?

To test and ensure that the overlays work as intended, ran commands:

• kustomize build components/odh-notebook-controller/config/overlays/service-mesh
• kustomize build components/notebook-controller/config/overlays/service-mesh

to ensure that
A: kustomize can build the overlay without errors
B: patches are applied correctly.

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

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[bartoszmajsak]

@harshad16 @VaishnaviHire It seems optimal to merge #172 initially, then address any subsequent conflicts/review our overlays, and test with the new target before proceeding with this. We plan to test those manifests in conjunction with the operator-v2 changes for the service mesh project we’re currently developing.

[cam-garrison]

Closing as we are incorporating these changes into PR #172 to keep it all in one PR.