helm: add Istio DestinationRule template for EPP service

[chewong]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Currently, users with an Istio Gateway must deploy a DestinationRule for each inference pool because, by default, EPP uses a self-signed certificate. This PR proposes adding the DestinationRule to the Helm Chart when .Values.provider.name is set to istio, similar to GKE's resources when provider is GKE and the DestinationRule deployed in the BBR Helm Chart here.

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

helm: add Istio DestinationRule template for EPP service

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: chewong
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[Gregory-Pereira]

dupe of #1381, please let me know if I am missing anything in my implementation

[chewong]

Looks good! I will close this PR.

/close

[k8s-ci-robot]

@chewong: Closed this PR.

In response to this:

Looks good! I will close this PR.

/close

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