roachtest: ssh_problem failed

roachtest.ssh_problem [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/17376626?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/17376626?buildTab=artifacts#/schemachange/leasing-benchmark) on release-24.3 @ [4cbedefd790c75cb0f21f77ed8d917c8528a7d15](https://github.com/cockroachdb/cockroach/commits/4cbedefd790c75cb0f21f77ed8d917c8528a7d15):

```
test schemachange/leasing-benchmark failed: (multiregion_leasing.go:185).func2: error persisted after 3 attempts: _potential_ SSH flake (``ssh -vvv`` log retained in /artifacts/schemachange/leasing-benchmark/run_1/ssh/ssh_083711.272178191_n3_time-p-cockroach-sql.log): TRANSIENT_ERROR(ssh_problem): exit status 255
test artifacts and logs in: /artifacts/schemachange/leasing-benchmark/run_1
```

Parameters:
- ROACHTEST_arch=amd64
- ROACHTEST_cloud=aws
- ROACHTEST_coverageBuild=false
- ROACHTEST_cpu=4
- ROACHTEST_encrypted=false
- ROACHTEST_fs=ext4
- ROACHTEST_localSSD=true
- ROACHTEST_runtimeAssertionsBuild=false
- ROACHTEST_ssd=0
Help

See: [roachtest README](https://github.com/cockroachdb/cockroach/blob/master/pkg/cmd/roachtest/README.md)

See: [How To Investigate \(internal\)](https://cockroachlabs.atlassian.net/l/c/SSSBr8c7)

_Grafana is not yet available for aws clusters_

Same failure on other branches

- #131724 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.2.4-rc]
- #131720 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1.6-rc]
- #129915 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-23.1.26-rc]
- #127118 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.2]
- #122095 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1]
- #112310 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-23.2]
- #108264 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-23.1]
- #90695 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-master]

/cc @cockroachdb/test-eng

[This test on roachdash](https://roachdash.crdb.dev/?filter=status:open%20t:.*ssh_problem.*&sort=title+created&display=lastcommented+project) | [Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-43378

Start with the retained ssh -vvv log at /artifacts/schemachange/leasing-benchmark/run_1/ssh/ssh_083711.272178191_n3_time-p-cockroach-sql.log and the failure reported at multiregion_leasing.go:185. Review the roachtest README and related reports, then run schemachange/leasing-benchmark to verify the SSH failure is diagnosed and no longer reproduces.

Written by the indexing model from the issue text.