[Subtask] TMS: In-job MaintenanceTypeHandler pipeline skeleton #13824

Describe the subtask

Add the in-job maintenance pipeline contract in plugins/tms so a single Spark Job can run an ordered chain of built-in types without inventing a second task-type enum:

• MaintenanceTypeHandler + AbstractMaintenanceTypeHandler (sample hooks gated by metrics capability)
• MaintenanceTypeOrchestrator (per type: sampleBefore → drift → shouldExecute → execute → sampleAfter; SKIP_TYPE / drift ends that type only)
• MaintenanceMetricsSupport (compaction + manifest-rewrite only)
• Four stub handlers (compaction, manifest-rewrite, snapshot-expiry, orphan-cleanup) + registry (commitChain / singleton)
• Unit tests for registry, metrics capability, and orchestrator control flow

Out of scope: Real S0 metrics persistence / recommend gate (#13777), BuiltInJob / Spark leaf execution, commit-chain OCC / validation metrics, scheduler / OccupancyGate.

Design: §5.2 in apache/gravitino#13386.

Parent issue

#13760