test(): Added unit test for pkg/cluster/node.go file

[Alokzh]

Description

This PR introduces comprehensive unit tests for the node IP discovery logic located in the pkg/cluster package.

How Has This Been Tested?

The new functionality has been validated through local unit testing

go test -v ./pkg/cluster/...
go test -v ./pkg/cluster/... -cover

The new tests for GetNodeIP verify several key scenarios, including:

• Correctly filtering for gateway nodes
• The fallback from ExternalIP to InternalIP
• Error handling when no nodes are found

Checklist:

• The title of the PR states what changed and the related issues number (used for the release note).
• Does this PR requires documentation updates?
• I've updated documentation as required by this PR.
• I have ran go fmt
• I have updated the helm chart as required by this PR.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have tested it for all user roles.
• I have added all the required unit test cases.
• I have verified the E2E test cases with new code changes.
• I have added all the required E2E test cases.

Does this PR introduce a breaking change?