roachtest: cdc/multiple-schema-changes failed

roachtest.cdc/multiple-schema-changes [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21476924?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21476924?buildTab=artifacts#/cdc/multiple-schema-changes) on release-25.4.15-rc @ [4913a926920d3003e1223156615a6a6a7d524b59](https://github.com/cockroachdb/cockroach/commits/4913a926920d3003e1223156615a6a6a7d524b59):

```
(test_runner.go:1493).runTest: test timed out (1h0m0s)
test artifacts and logs in: /artifacts/cdc/multiple-schema-changes/run_1
```

Parameters:
- arch=amd64
- cloud=gce
- coverageBuild=false
- cpu=16
- encrypted=false
- fs=ext4
- localSSD=true
- metamorphicBufferedSender=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-21476924/cdc-multiple-schema-changes/1787294931040/1787298692425)

/cc @cockroachlabs/cdc

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

Start with the roachtest README and the failure at test_runner.go:1493, then inspect the artifacts and logs under /artifacts/cdc/multiple-schema-changes/run_1. Use the linked Grafana view and the cdc/multiple-schema-changes test entry point to determine why it exceeded the one-hour timeout. Done means the failure is understood and the test passes reliably on the affected release branch.

Written by the indexing model from the issue text.