release-26.3.1-rc: roachtest: backup-restore/mixed-version failed

roachtest.backup-restore/mixed-version [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21478923?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21478923?buildTab=artifacts#/backup-restore/mixed-version) on release-26.3.1-rc @ [aa630a5a7eab6feb41e1b627121c1cb0575c2e47](https://github.com/cockroachdb/cockroach/commits/aa630a5a7eab6feb41e1b627121c1cb0575c2e47):

Failed with:

```
(test_runner.go:1589).runTest: test timed out (8h0m0s)
test artifacts and logs in: /artifacts/backup-restore/mixed-version/run_1
```
Cluster Node to Ip Mapping:
| Node | Public IP | Private IP |
| --- | --- | --- |
| teamcity-21478923-1787461710-19-n5cpu4-0001 | | 10.91.96.10 |
| teamcity-21478923-1787461710-19-n5cpu4-0002 | | 10.91.98.133 |
| teamcity-21478923-1787461710-19-n5cpu4-0003 | | 10.91.98.134 |
| teamcity-21478923-1787461710-19-n5cpu4-0004 | | 10.91.96.24 |
| teamcity-21478923-1787461710-19-n5cpu4-0005 | | 10.91.98.1 |

Parameters:
- arch=amd64
- cloud=gce
- coverageBuild=false
- cpu=4
- diskCount=0
- encrypted=true
- fs=ext4
- localSSD=true
- mvtDeploymentMode=shared-process
- mvtVersions=v25.2.18 → v25.3.7 → v25.4.10 → v26.2.1 → v26.3.1-dev-aa630a5a7eab6feb41e1b627121c1cb0575c2e47 (release-26.3.1-rc)
- runtimeAssertionsBuild=false
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-21478923/backup-restore-mixed-version/1787463465411/1787492646143)

See: [Datadog Logs](https://us5.datadoghq.com/logs?query=service%3Aroachtest+%40cluster%3Ateamcity-21478923-1787461710-19-n5cpu4&from_ts=1787463465411&to_ts=1787492646143&live=false&storage=flex_tier)

Same failure on other branches

- #173559 roachtest: backup-restore/mixed-version failed [A-disaster-recovery B-runtime-assertions-enabled C-bug C-test-failure O-roachtest O-robot P-2 T-kv backport-24.1.x backport-24.3.x backport-25.2.x backport-25.3.x branch-release-25.4]
- #172161 roachtest: backup-restore/mixed-version failed [A-disaster-recovery B-runtime-assertions-enabled C-test-failure O-roachtest O-robot P-3 T-disaster-recovery branch-release-25.2]
- #170322 roachtest: backup-restore/mixed-version failed [A-disaster-recovery B-runtime-assertions-enabled C-test-failure O-roachtest O-robot P-2 T-disaster-recovery branch-release-26.1]

/cc @cockroachlabs/disaster-recovery

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

Jira issue: CRDB-67079