feature (iceberg): Implement TRUNCATE TABLE for Iceberg Engine (REST …

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Changelog category (leave one):

• New Feature

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

Frontport for Antalya 26.3

• 26.1 Antalya port - Implement TRUNCATE TABLE for Iceberg Engine (REST catalog support) Feature: Support TRUNCATE TABLE for Iceberg engine #1529, It's a frontport from 26.1, contains:
  • feat(iceberg): Implement TRUNCATE TABLE for Iceberg Engine (REST catalog support) — Core implementation: metadata-only truncation generating a new overwrite snapshot with empty manifest list, committed atomically via REST catalog
  • fix(iceberg): pass new_snapshot to updateMetadata in IcebergStorageSink — Fixed silent breakage of all INSERTs on REST catalog tables (wrong JSON object passed to catalog->updateMetadata)
  • fix(iceberg): restore return false in RestCatalog::updateMetadata — Preserve retry contract; add LOG_WARNING for diagnostics
  • fix(iceberg): revert Mutations.cpp updateMetadata to pass new_snapshot — Same fix as IcebergStorageSink, applied to ALTER TABLE DELETE/UPDATE path
  • refactor(iceberg): add comment explaining Avro zigzag encoding — Reviewer-requested documentation for manual Avro OCF serialization
  • refactor(iceberg): address code review feedback on TRUNCATE implementation — Named zero arguments, helper functions, restart integration test

Adaptation notes for antalya-26.3

The following API changes between antalya-26.1 and antalya-26.3 required adaptation:

• RestCatalog constructor signature updated to match antalya-26.3 calling convention in DataLakeConfiguration.h
• DatabaseDataLakeSetting member names updated
• Cargo.lock restored to antalya-26.3 version (our changes do not touch any Rust code)

All feature logic is identical to the merged antalya-26.1 implementation.

CI/CD Options

Exclude tests:

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

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• S3 Export (2h)
• Swarms (30m)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [e229240]

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On CI Failures & Asking a review

Flagging the CI failures for review. All observed failures are pre-existing and unrelated to the Iceberg TRUNCATE changes in this PR.

03706_statistics_preserve_checksums_on_mutations
MergeTree checksum mismatch in Statistics/mutations code path. The full stack trace contains no Iceberg frames. Pre-existing flaky test unrelated to this diff.

Docker CVEs (CVE-2026-28388, CVE-2026-28389, CVE-2026-28390, CVE-2026-31790, CVE-2026-40200)
Grype scan failures against the Alpine base image:

• openssl 3.3.6-r0 — fixed in 3.3.7-r0 (CVEs 28388/28389/28390/31790)
• musl 1.2.5-r9 — fixed in 1.2.5-r11 (CVE-2026-40200)

These require a base image update by the Docker/infra team and are unrelated to any C++ code changes in this PR. The same CVEs appear on the base antalya-26.3 branch independently of this PR.

This PR is a forward-port of the Iceberg TRUNCATE TABLE feature from antalya-26.1 (merged as PR #1529), adapted for antalya-26.3 API changes. All 19 integration tests pass including test_iceberg_truncate and test_iceberg_truncate_restart.