release-22.2: kvserver: improve system lease observability

[erikgrinaker]

Backport 2/2 commits from #104008.

/cc @cockroachdb/release

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kvserver: add leases.liveness metric

This patch adds the metric leases.liveness tracking the number of liveness range leases per node (generally 1 or 0). This is useful to find out which node had the liveness lease at a particular time.

I ran a 10k range cluster to look at the CPU cost of the key comparisons, it didn't show up on CPU profiles.

Epic: none
Release note (ops change): added the metric leases.liveness showing the number of liveness range leases per node (generally 1 or 0), to track the liveness range leaseholder.

kvserver: log system range lease acquisition

This patch logs acquisition of meta/liveness range leases to the health log. These leases are critical to cluster health, and during debugging it's useful to know their location over time.

Resolves #99472.

Epic: none
Release note: none

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is 

[erikgrinaker]

Unclean metrics backport (the calcReplicaMetrics bit), but I think I got it right.