fix(bbr): enable response header/body processing in Istio EnvoyFilter

[abdallahsamabd]

What type of PR is this?

/kind bug

What this PR does / why we need it:

The Istio EnvoyFilter configuration for BBR had response_header_mode: "SKIP" and response_body_mode: "NONE", which meant Envoy never forwarded response headers or body to the BBR ext_proc server. This prevented response plugins (added in #2369, #2477) from being invoked at all.

This PR updates the processing mode to:

• response_header_mode: "SEND"
• response_body_mode: "FULL_DUPLEX_STREAMED"

Which issue(s) this PR fixes:

Does this PR introduce a user-facing change?:

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[k8s-ci-robot]

Hi @abdallahsamabd. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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[nirrozenbaum]

/ok-to-test

[nirrozenbaum]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: abdallahsamabd, nirrozenbaum

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