release-26.2.5-rc: roachtest: backup/ceph/reef/plain failed

**Note:** This build has runtime assertions enabled. If the same failure was hit in a run without assertions enabled, there should be a similar failure without this message. If there isn't one, then this failure is likely due to an assertion violation or (assertion) timeout.

roachtest.backup/ceph/reef/plain [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyGceBazel/21437715?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyGceBazel/21437715?buildTab=artifacts#/backup/ceph/reef/plain) on release-26.2.5-rc @ [0996c85a8557204febcf99cef0ada1a5e147d0e0](https://github.com/cockroachdb/cockroach/commits/0996c85a8557204febcf99cef0ada1a5e147d0e0):

Failed with:

```
(cluster.go:2708).Run: full command output in run_105318.153384914_n4_sudo-radosgwadmin-ke.log: COMMAND_PROBLEM: exit status 139
test artifacts and logs in: /artifacts/backup/ceph/reef/plain/run_1
```
Cluster Node to Ip Mapping:
| Node | Public IP | Private IP |
| --- | --- | --- |
| teamcity-21437715-1784889982-16-n4cpu4-0001 | 34.26.148.80 | 10.142.2.46 |
| teamcity-21437715-1784889982-16-n4cpu4-0002 | 34.23.222.44 | 10.142.2.36 |
| teamcity-21437715-1784889982-16-n4cpu4-0003 | 34.24.149.18 | 10.142.2.35 |
| teamcity-21437715-1784889982-16-n4cpu4-0004 | 34.23.18.13 | 10.142.2.215 |

Parameters:
- arch=amd64
- cloud=gce
- coverageBuild=false
- cpu=4
- diskCount=0
- encrypted=true
- fs=ext4
- localSSD=true
- metamorphicLeases=epoch
- metamorphicWriteBuffering=true
- runtimeAssertionsBuild=true
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-21437715/backup-ceph-reef-plain/1784890283698/1784890577350)

Same failure on other branches

- #172385 release-26.3: roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-26.3]
- #169620 release-26.2: roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-26.2]
- #169617 roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-master]
- #169614 roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-25.4]
- #169610 roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-26.1]
- #169605 roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-25.4.10-rc]
- #169602 roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-25.2]
- #169598 roachtest: backup/ceph/reef/plain failed [C-test-failure O-roachtest O-robot T-field-eng branch-release-24.3]

/cc @cockroachlabs/field-engineering

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

Jira issue: CRDB-66050

Start with the roachtest README and the linked TeamCity log, especially run_105318.153384914_n4_sudo-radosgwadmin-ke.log, then inspect the artifacts under /artifacts/backup/ceph/reef/plain/run_1. Trace the backup/ceph/reef/plain test and reproduce the exit-status-139 failure; done means the failure is explained and the test passes reliably on the affected branches.

Written by the indexing model from the issue text.