fix: respect namespace in structured local-gateways config

[DCchoudhury15]

Changes

• Fixed a bug where the Operator ignored the namespace field when using the structured local-gateways configuration format.
• Updated UpdateNamespace logic in ingress_service.go to unmarshal and prioritize the plural local-gateways YAML array.
• Added unit tests in ingress_service_test.go to verify structured config parsing and ensure it takes precedence over legacy dot-notation config.

/kind bug

Fixes #2201

Release Note

Fixed an issue where the Knative Operator ignored the namespace field in the structured local-gateways configuration, defaulting incorrectly to istio-system.

[knative-prow]

Welcome @DCchoudhury15! It looks like this is your first PR to knative/operator 🎉

[knative-prow]

Hi @DCchoudhury15. Thanks for your PR.

I'm waiting for a github.com 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. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[knative-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: DCchoudhury15
Once this PR has been reviewed and has the lgtm label, please assign dsimansk for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment