fix(tests): isolate state in test_write_optional_list

`test_write_optional_list` uses `create_table_if_not_exists` and then asserts
exact row counts after two `tbl.append()` calls. On any subsequent run the
table is reused, so the asserted counts (2, then 4) become 6, 10, ... and the
test fails. The failure only surfaces when the integration suite is replayed
without a fresh docker-compose stack, which masks the bug in CI but makes it a
papercut for local development.

Drop the table at the start to guarantee a clean slate, matching the pattern
used by `_create_table()` for every other write test in this module.

Author: Paul Mathew

tests/integration/test_writes/test_writes.py

@@ -2027,7 +2027,7 @@ def test_write_optional_list(session_catalog: Catalog) -> None:
             required=False,
         ),
     )
-    session_catalog.create_table_if_not_exists(identifier, schema)
+    _create_table(session_catalog, identifier, schema=schema)
 
     df_1 = pa.Table.from_pylist(
         [