[EPIC] Iceberg REST Spec Compliance Gaps in Gravitino

### Describe the proposal

Gravitino still has some gap between the Iceberg REST specWhile Gravitino provides an Iceberg REST catalog service that follows the Apache Iceberg REST API specification, there are still notable gaps between its current implementation and the full Iceberg REST spec. These gaps limit full compatibility with the broader Iceberg ecosystem and tools that expect complete REST spec adherence.

### Task list

- [ ] #9736

Begin with task #9736 and compare Gravitino's Iceberg REST catalog service with the relevant REST specification requirements. No source file or test is named; done means the identified compliance gaps are addressed and the service is validated against the spec.

Written by the indexing model from the issue text.