[#11194] feat(maintenance): Add builtin-iceberg-expire-snapshots job

[laserninja]

What changes were proposed in this pull request?

Add a new built-in Iceberg maintenance job builtin-iceberg-expire-snapshots that expires old snapshots from Iceberg tables via Spark's expire_snapshots procedure.

Changes:

• New IcebergExpireSnapshotsJob class in maintenance/jobs following the same pattern as IcebergRewriteDataFilesJob
• Supports configurable parameters: older_than (timestamp), retain_last (number of snapshots to keep), stream_results (boolean)
• SQL injection protection via escapeSqlString() and escapeSqlIdentifier()
• Input validation for retain_last (must be positive integer) and stream_results (must be true/false)
• Registered in BuiltInJobTemplateProvider

Why are the changes needed?

Without periodic snapshot expiration, Iceberg table metadata grows indefinitely, accumulating snapshot JSON files and manifest lists that slow down table operations and waste storage. The existing built-in jobs (builtin-iceberg-rewrite-data-files and builtin-iceberg-update-stats) cover data compaction and metrics but do not address metadata cleanup.

This is one of the most critical Iceberg housekeeping operations. PR #10500 added Trino-side delegation for expire_snapshots as a procedure, but there is no server-side built-in job that can be triggered automatically via the Optimizer.

Fix: #11194

Note: This PR covers the job layer. The end-to-end policy/strategy integration (e.g. IcebergSnapshotExpirationContent, SnapshotExpirationStrategyHandler) can be added as a follow-up, as discussed in the issue.

Does this PR introduce any user-facing change?

No user-facing API changes. Adds a new built-in job template builtin-iceberg-expire-snapshots that will be available for maintenance job scheduling.

How was this patch tested?

• Added TestIcebergExpireSnapshotsJob with 40 unit tests covering:
  • Job template metadata (name, comment, executable, mainClass, arguments, sparkConfigs, version)
  • Argument parsing (required, optional, empty values, missing values, all options, order independence)
  • Procedure call building (minimal, with older-than, retain-last, stream-results, all params, empty params)
  • SQL escaping and injection prevention
  • Input validation for retain-last and stream-results
  • Custom Spark config parsing (valid JSON, numeric values, empty, null, invalid JSON)
• All 142 tests in maintenance:jobs module pass with 0 failures

[github-actions]

Code Coverage Report

Overall Project	72.22% -0.52%	🟢
Files changed	60.26%	🟢

Module	Coverage
jobs	64.09% -1.3%	🟢
optimizer	82.95%	🟢
optimizer-api	21.95%	🔴

Files

Module	File	Coverage
jobs	BuiltInJobTemplateProvider.java	81.82%	🟢
	IcebergExpireSnapshotsJob.java	56.59%	🔴