Set EPP NAMESPACE env var in helm charts

[liu-cong]

What would you like to be added:
Right now the default pool-namespace is set to default, however this is typically the namespace that EPP pod runs in.

gateway-api-inference-extension/pkg/epp/server/runserver.go

Line 73 in 7108536

DefaultPoolNamespace = "default" // default for --pool-namespace

Instead, we can:

• Use the specified namespace if provided.
• If the flag is not provided, use the value from a NAMESPACE env var which can be derived from the metadata like so:

env:
        - name: NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace

• If the env var is not provided, fall back to default

Why is this needed:

This provides a convenient default without the need to explicitly set when running in a namespace other than default.

[ahg-g]

/triage accepted
/good-first-issue

[k8s-ci-robot]

@ahg-g:
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/good-first-issue

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[sureshkrishnan-v]

Hi, can i work on this feature as a new contributer it would be great if any one guides me

[thudoan1706]

/assign

[liu-cong]

#1578

[ahg-g]

We still need to add the env var to the helm chart, right?