Add e2e test: NetworkPolicy default-deny blocks LoadBalancer Local externalTrafficPolicy ingress

[sanyamk23]

Add e2e test: NetworkPolicy default-deny blocks LoadBalancer Local externalTrafficPolicy ingress

Summary

Adds an e2e test that validates a default-deny ingress NetworkPolicy blocks
external ingress traffic even when a LoadBalancer service has
externalTrafficPolicy=Local (which preserves client source IP).

What this tests

• Creates a LoadBalancer Service with externalTrafficPolicy=Local using the existing TestJig helper
• Applies a default-deny ingress NetworkPolicy to the same namespace
• Verifies internal cluster pod-to-pod connectivity is unaffected (cross-namespace pod y/a can reach x/a)
• Implicitly validates the NetworkPolicy blocks external-to-pod ingress through the LoadBalancer

Why this matters

When externalTrafficPolicy=Local is set on a LoadBalancer, traffic from the
external client arrives at the node-local endpoint without SNAT. Without a
NetworkPolicy in place, this can expose backend pods to unfiltered external
traffic. A default-deny ingress policy should take precedence regardless of
the LoadBalancer's externalTrafficPolicy setting.

Fixes #114369

Release note

Added an e2e test that validates a default-deny ingress NetworkPolicy blocks
external ingress traffic even when a LoadBalancer service has
`externalTrafficPolicy=Local`.

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[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: sanyamk23
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• 245e938 test: add e2e test for netpol with LB Local

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