Close input readers when ParquetRewriter setup fails

### Describe the bug, including details regarding any error messages, version, and platform.

`ParquetRewriter.getFileReaders` opens each input reader into a local list. If opening a later input throws `IOException`, the exception is propagated without closing readers already opened for earlier inputs. Because construction fails, callers cannot close those readers, which leaks their input streams.

Expected behavior: readers opened before the failure are closed before the setup exception is propagated.

### Component(s)

Core

Start at ParquetRewriter.getFileReaders and trace how input readers are opened and how setup IOExceptions are propagated. Verify that readers opened before a failure are closed before the exception escapes, then run the focused tests for ParquetRewriter or Core to confirm the setup-failure behavior.

Written by the indexing model from the issue text.