Do not persist data to memory by default when creating tables

[jdye64]

Currently data is persisted into memory when create_table is invoked. Instead this PR will set the default for persist to False which will prevent that from happening.

This Closes: #218

[charlesbluca]

Now that #240 is merged, you should revert efa492f, as it retains some bugs from the initial setup of gpuCI

[ayushdg]

Could you update the doctstring in the params section here as well:

dask-sql/dask_sql/context.py

Line 188 in 475ee7d

persist (:obj:`bool`): Only used when passing a string into the ``input`` parameter.

[jdye64]

Could you update the doctstring in the params section here as well:

dask-sql/dask_sql/context.py

Line 188 in 475ee7d

persist (:obj:`bool`): Only used when passing a string into the ``input`` parameter.

Yep, just flipped around the values from False -> True and off->on since the rest of the doc string is still valid.

[jdye64]

rerun tests

[charlesbluca]

LGTM, thanks @jdye64! Will merge in once tests finish up