roachtest: monitor_failure failed

roachtest.monitor_failure [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyGceBazel/20347355?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyGceBazel/20347355?buildTab=artifacts#/backup-restore/mixed-version) on release-25.3.1-rc @ [a6493dfe270695ee58648b86fb51ff2ff7c8a718](https://github.com/cockroachdb/cockroach/commits/a6493dfe270695ee58648b86fb51ff2ff7c8a718):

```
test backup-restore/mixed-version failed: (test_monitor.go:35).func1: test monitor: EOF [owner=test-eng]
(test_runner.go:1420).runTest: test timed out (8h0m0s)
test artifacts and logs in: /artifacts/backup-restore/mixed-version/cpu_arch=arm64/run_1
```

Parameters:
- arch=arm64
- cloud=gce
- coverageBuild=false
- cpu=4
- encrypted=false
- fs=ext4
- localSSD=false
- mvtDeploymentMode=separate-process
- mvtVersions=v24.2.10 → v24.3.18 → v25.1.10 → v25.2.4 → release-25.3.1-rc
- 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-20347355/backup-restore-mixed-version/1755236857825/1755266737303)

Same failure on other branches

- #151630 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1.23-rc]
- #150925 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3]
- #150732 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3.0-rc]
- #147884 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.2]
- #146627 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1.19-rc]
- #143828 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.1.3-rc]
- #142946 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.1.2-rc]
- #142510 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.1.1-rc]
- #142507 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.1.14-rc]
- #141693 roachtest: monitor_failure failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.3.7-rc]

/cc @cockroachdb/test-eng

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

Jira issue: CRDB-53537