kvserver: log when raft send/recv queue fills up

[tbg]

Inspired by https://github.com/cockroachlabs/support/issues/1770.

If either the raft send or receive queue fills up, wide-spread outages
can occur as replication progress stalls. We have metrics that can
indicate this, but straightforward logging is also appropriate to direct
attention to the fact, which this commit achieves.

Touches #79755

Release justification: important logging improvement
Release note: None

[cockroach-teamcity]

This change is 

[tbg]

TFTRs!
bors r=erikgrinaker

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[craig]

Build failed:

• Bazel Essential CI (Cockroach)

[tbg]

bors r=pavelkalinnikov

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)

[tbg]

blathers backport 21.2

[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

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error creating merge commit from c1cd955 to blathers/backport-release-21.2-86645: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 21.2 failed. See errors above.

---

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[tbg]

blathers backport 22.1

[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

---

error creating merge commit from c1cd955 to blathers/backport-release-22.1-86645: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 22.1 failed. See errors above.

---

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