fix(metric): Update dynamic interface label to be constant

[BeegiiK]

Description

Updated dynamic interface label for interface_stats metric to be set to all_interfaces. Also did some optimisation on the EthtoolStats struct. All stat names will be accumulated across all interface names

Related Issue

#1067

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.

[huntergregory]

I'm assuming you need to modify e2e tests? If not, we have a test gap. Otherwise, lgtm, but I would also suggest you manually test this on a cluster and see the metric output before merging?

Also, not sure why tests are being skipped?

[BeegiiK]

I'm assuming you need to modify e2e tests? If not, we have a test gap. Otherwise, lgtm, but I would also suggest you manually test this on a cluster and see the metric output before merging?

Also, not sure why tests are being skipped?

I verified it manually on a cluster:

Although, I needed to prevent the processStats from being called to get these results as I could not find a clear approach to retrieve results without the filter being called. The unit tests also pass.

One thing I observed, I did a check to see what interfaces are being monitored (pre-filtering, i.e. before processStats is called) and found only two are watched, with my change it will be a 50% reduction. I guess since Retina is always filtering, leaving no stats unless criteria is met, we won't know the full impact of the change.

Those e2e tests are usually skipped at the PR level (not sure why) and it's been like this for quite some time.