[Improvement] Revisit Iceberg properties managed by Gravitino

### What would you like to be improved?

`identifier-fields` should not be reserved, `format-version` should be mutable, `provider` and `format` should be generated in spark connector side not Gravitino side.

### How should we improve?

_No response_

Start by tracing how Iceberg properties are handled in Gravitino and in the Spark connector, focusing on the property-management entry points named in the issue. Determine where reservation, mutability, and generation are currently enforced; done means the four listed properties follow the requested ownership and mutability rules.

Written by the indexing model from the issue text.