roachtest: ssh_problem failed

roachtest.ssh_problem [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyGceBazel/20584289?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyGceBazel/20584289?buildTab=artifacts#/follower-reads/mixed-version/single-region) on release-25.3.3-rc @ [eee1425c7947789ebb486acc3528751d7f3c112e](https://github.com/cockroachdb/cockroach/commits/eee1425c7947789ebb486acc3528751d7f3c112e):

```
test follower-reads/mixed-version/single-region failed: (test_runner.go:850).func4: cluster.PutE: put "/go/src/github.com/cockroachdb/cockroach/bin/cockroach.linux-amd64" failed: error persisted after 2 attempts: TRANSIENT_ERROR(ssh_problem): ~ scp -r -C -o StrictHostKeyChecking=no -o ConnectTimeout=10 -i /home/roach/.ssh/id_rsa /go/src/github.com/cockroachdb/cockroach/bin/cockroach.linux-amd64 ubuntu@34.75.240.79:./cockroach
Warning: Permanently added '34.75.240.79' (ECDSA) to the list of known hosts.
client_loop: send disconnect: Broken pipe
lost connection: exit status 1 [owner=test-eng]
```

Parameters:
- arch=amd64
- cloud=gce
- coverageBuild=false
- cpu=2
- encrypted=false
- fs=ext4
- localSSD=true
- runtimeAssertionsBuild=false
- 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)

See: [Grafana](https://go.crdb.dev/roachtest-grafana/teamcity-20584289/follower-reads-mixed-version-single-region/-62135596800000/-62135596680000)

Same failure on other branches

- #154854 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1.25-rc]
- #154612 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.3.21-rc]
- #154528 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.4]
- #153154 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1.24-rc]
- #153147 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.3.20-rc]
- #153140 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.2.6-rc]
- #152951 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3.2-rc]
- #152321 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.3.19-rc]
- #152156 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3.1-rc]
- #151647 roachtest: ssh_problem failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.2.5-rc]

/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-55291

Start with the roachtest README and the failure at test_runner.go:850, then inspect the linked TeamCity log and artifacts for the broken scp connection. Compare the repeated ssh_problem reports on other branches and use the linked investigation guide and Grafana data. Done means the underlying failure is addressed and the follower-reads/mixed-version/single-region test no longer reports this SSH problem.

Written by the indexing model from the issue text.