Use `multiprocessing.Pool` in `test_read_text` (#7472)
Use `multiprocessing.Pool` in `test_read_text` (#7472)

* Use `multiprocessing.Pool` in `test_read_text`

As this is being used with Dask's local scheduler, we can't make this
change while the local scheduler relies on `apply_async`. So revert for
now.

* test-hdfs
jakirkham/dask,dask/dask,dask/dask,blaze/dask,jakirkham/dask,blaze/dask