release-26.1: roachtest: use title override for schema change workload failures

[msbutler]

Backport 1/1 commits from #169578 on behalf of @msbutler.

---

Schema change workload failures in DR roachtests (backup-restore,
c2c) are rerouted to sql-foundations via ErrorWithOwner. However,
since issue deduplication is title-based, a subsequent non-schema-change
failure would match the existing sql-foundations issue instead of
creating a new one for disaster-recovery.

Add a TitleOverride so schema change workload failures get a distinct
issue title ("schema_change_workload_failure"), preventing dedup
collisions with real DR test failures.

Epic: none
Release note: None

---

Release justification: test only change

[blathers-crl]

Thanks for opening a backport.

Before merging, please confirm that the change does not break backwards compatibility and otherwise complies with the backport policy. Include a brief release justification in the PR description explaining why the backport is appropriate. All backports must be reviewed by the TL for the owning area. While the stricter LTS policy does not yet apply, please exercise judgment and consider gating non-critical changes behind a disabled-by-default feature flag when appropriate.

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[cockroach-teamcity]

This change is 

[blathers-crl]

Detected infrastructure failure (matched: self-hosted runner lost communication with the server). Automatically rerunning failed jobs. (run link)

[herkolategan]

Requires --rewrite to address the unit test failures on CI.

[blathers-crl]

Detected infrastructure failure (matched: self-hosted runner lost communication with the server). Automatically rerunning failed jobs. (run link)