Consolidate MetricsDataSet

[astrojuanlu]

Description

In principle defining MetricsDataSet on kedro-viz would make some sense for now, but ultimately experiment tracking should be consumable by tools other than kedro-viz and so I don't think this would make sense longer term. More practically, it would be a huge breaking change and almost definitely not worth the cost for a small benefit. So I'd rather that we solve the underlying issue by defining what MetricsDataSet._load should do and keep it in kedro-datasets instead.

Originally posted by @antonymilne in #1352 (comment)

Context

A user (and myself) were baffled at the current monkeypatching behavior, which took a full day of debugging for an unexperienced eye to diagnose. See discussion at #1352

[antonymilne]

N.B. this will need a few big decisions about how experiment tracking works to be made first - see my point two in #1217. The future of these datasets isn't clear to anyone I think, and so we shouldn't add any functionality to them unless they are destined to stay.

[astrojuanlu]

Another internal user just asked about this as well https://quantumblack.slack.com/archives/C7JTFSFUY/p1685549279866579

[merelcht]

Do we still want to do something about MetricsDataset or leave it as is for now as the role of experiment tracking is also still undecided?

[astrojuanlu]

I think we should move it to Kedro Viz. We have mentioned this possibility somewhere already.

[rashidakanchwala]

We can close this ticket as the original problem #1352 has been resolved in this PR #1698