Log the first failed CAS blob publication attempt below Warning

[filimonov]

The per-attempt CasBlobPublishAttempt warning of #2555 reached clients with send_logs_level=warning and failed two stateless tests on stderr in stateless asan cas s3 2/2: 02907_filter_pushdown_crash and 03254_pr_join_on_dups. Both saw Publication of CAS blob ... failed, attempt 1 of 8: ... Connection refused; attempt 2 succeeded.

The first failed attempt is now logged at Information. Attempt 2 and later, and the give-up path, stay at Warning. CASBlobPublishAttemptFailed and CASBlobPublishGaveUp are unchanged.

Test: CASBlobPublishTransport.FirstFailedAttemptIsBelowWarning drops two PutObject responses and checks that attempt 1 is absent and attempt 2 present in a Warning-level capture. It failed before the change (attempt 1 logged once).

Related: #2555

Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

CAS blob publication logs the first failed attempt at Information instead of Warning, so a single retried failure no longer reaches clients that request warning-level logs.

Documentation entry for user-facing changes

• Not needed: the docs do not state the log level.

CI/CD Options

Exclude tests:

• Fast test
• Integration Tests
• Stateless tests
• Stateful tests
• Unit tests
• Performance tests
• Aarch64 tests
• All with ASAN
• All with TSAN
• All with MSAN
• All with UBSAN
• All with Coverage
• All Regression
• Disable CI Cache

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• CAS (content-addressed storage; Antalya only)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• OAuth (5m)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• S3 Export (2h)
• Swarms (30m)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [6a1085e]