test: Run e2e tests in both arm64 and amd64 arch.

[jimassa]

Description

This PR allows us to run plugin e2e in both arm64 and amd64 arch.
It also replaces agnhost image with the standard one hosted in registry.k8s.io/e2e-test-imagesinstead of the fork in acnpublic, as it is multi-arch and good practice.

The test sets up agnhost in different args, and check plugin metrics on retina-agent on both amd64 and arm64.

Related Issue

If this pull request is related to any issue, please mention it here. Additionally, make sure that the issue is assigned to you before submitting this pull request.

#450

Checklist

• I have read the contributing documentation.
• I signed and signed-off the commits (git commit -S -s ...). See this documentation on signing commits.
• I have correctly attributed the author(s) of the code.
• I have tested the changes locally.
• I have followed the project's style guidelines.
• I have updated the documentation, if necessary.
• I have added tests, if applicable.

Screenshots (if applicable) or Testing Completed

Please add any relevant screenshots or GIFs to showcase the changes made.

Additional Notes

Add any additional notes or context about the pull request here.

---

Please refer to the CONTRIBUTING.md file for more information on how to contribute to this project.

[Copilot]

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 suggestion.

Files not reviewed (1)

• test/e2e/common/common.go: Evaluated as low risk