[🐞] Collection of a few bugs

[kevinjqliu]

Apache Iceberg version

None

Please describe the bug 🐞

While working on a Python REST server implementation (https://github.com/kevinjqliu/iceberg-rest-catalog), I noticed a few Pyiceberg bugs while integrating with PySpark. The REST server implementation is using SqlCatalog as the underlying catalog.

Here's the collection of bugs that I would like to upstream (https://github.com/apache/iceberg-python/compare/main...kevinjqliu:iceberg-python:kevinjqliu/iceberg-rest-catalog) To summarize:

• [ ] rest.py's drop_namespace function is missing handling the 409 status code. (#868)
• [ ] sql.py's drop_namespace function does not return NoSuchNamespaceError when namespace is missing. (#865)
• [ ] sql.py's update_namespace_properties function only updates the first property and drops the rest. (#873)
• [ ] TableMetadata is initialized with the default Pydantic object for schema, partition_spec, and sort_order, which does not play well with table updates.

I'll be happy to work on this but I think these are "good first issues". We can break these up into separate PRs with the relevant tests.

[uatach]

@kevinjqliu, I've just created a PR for the second item on the list.

[ranli]

@kevinjqliu created a PR to fix 3rd item on the list