release-22.2: kv: remove broken attempt to reject lease acquisitions on draining nodes

[blathers-crl]

Backport 1/1 commits from #87885 on behalf of @nvanbenschoten.

/cc @cockroachdb/release

---

Related to #83261.

This commit removes "protection" that avoided lease acquisitions on draining nodes. This protection had already been effectively disabled by acc1ad1, which allowed Raft leaders to bypass the check. As the comment here (added in 5ffaa9e) explained, Raft followers are already unable to acquire the lease. If leaders bypass the check and follower (and candidates) don't need it, the check is useless, so we remove it.

The commit also removes TestReplicaDrainLease, which was supposed to test this behavior. We remove the test not because it started failing after the change, but because it did not. It must not have been testing anything real anymore after acc1ad1.

Release justification: low risk change related to release blocker.

Release note: None

---

Release justification:

[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?

[cockroach-teamcity]

This change is 

[nvanbenschoten]

I've decided not to backport this. It's not needed in v22.2 and it posses a small risk of unintentional log spam.