Move Dask config overrides to sql.yaml (#1260)

* Move dataframe overrides to sql.yaml

* Un-xfail test_xgboost_training_prediction on win32

* Revert "Un-xfail test_xgboost_training_prediction on win32"

This reverts commit 16ca14f.

* Move overrides to import-time

* Add config overrides back to conftest.py

dask_sql/__init__.py

@@ -4,12 +4,17 @@
 
 import importlib.metadata
 
+from dask.config import set
+
 from . import config
 from .cmd import cmd_loop
 from .context import Context
 from .datacontainer import Statistics
 from .server.app import run_server
 
+# TODO: get pyarrow strings and p2p shuffle working
+set(dataframe__convert_string=False, dataframe__shuffle__method="tasks")
+
 __version__ = importlib.metadata.version(__name__)
 
 __all__ = [__version__, cmd_loop, Context, run_server, Statistics]