Add integration tests for transaction APIs

### Is your feature request related to a problem or challenge?

Now many APIs in `transaction/mod.rs` don't have an integration tests to test if they actually work after committing the transaction. We can probably create a new test to test these APIs using a memory catalog

### Describe the solution you'd like

_No response_

### Willingness to contribute

I would be willing to contribute to this feature with guidance from the Iceberg Rust community

Start in transaction/mod.rs and identify the transaction APIs that lack integration coverage. Use a memory catalog to exercise those APIs after committing the transaction; done means the relevant APIs have integration tests demonstrating that their committed behavior works.

Written by the indexing model from the issue text.