storage: node liveness records shouldn't use MVCC

[andreimatei]

These records currently use MVCC, but that seems ridiculous. We're wasting space and causing splits in a sensitive region of the key space.
I think we should move away from MVCC, but I'm not entirely sure about how the migration would work. @tbg have you ever thought about this?

I've also found this random note that wants the liveness record key prefix changed, which perhaps could be done at the same time.
#18276 (comment)

cc @nvanbenschoten

Jira issue: CRDB-4421

[tbg]

I agree that MVCC isn't useful here. My expectation is that we'll move away from node liveness (for example to @andy-kimball's proposed failure detector) and that it won't be worth it to do something in the interim (was this issue motivated by something, for example a stability problem? I know we've had some in the past, but thought we had successfully worked around them for now).
Which splits do you mean? The liveness range itself can't be split.

[andreimatei]

was this issue motivated by something, for example a stability problem?

No, it wasn't motivated by anything in particular.

Which splits do you mean? The liveness range itself can't be split.

I was actually wondering about that. I thought it wouldn't, but then I couldn't find what prevents it. Now I did.

[github-actions]

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[knz]

definitely still relevant

[github-actions]

We have marked this issue as stale because it has been inactive for
18 months. If this issue is still relevant, removing the stale label
or adding a comment will keep it active. Otherwise, we'll close it in
10 days to keep the issue queue tidy. Thank you for your contribution
to CockroachDB!

[knz]

cc @andrewbaptist