Revert "feat: Add "transfer_manager" module for concurrent uploads and downloads as a preview feature (#844)" (#897)

This reverts commit 9dcc684.

Author: cojenco

google/cloud/storage/constants.py

@@ -11,7 +11,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
 """Constants used across google.cloud.storage modules."""
 
 # Storage classes

google/cloud/storage/fileio.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Module for file-like access of blobs, usually invoked via Blob.open()."""
+"""Support for file-like I/O."""
 
 import io
 import warnings
@@ -101,12 +101,10 @@ class BlobReader(io.BufferedIOBase):
         - ``if_metageneration_match``
         - ``if_metageneration_not_match``
         - ``timeout``
-
-        Note that download_kwargs are also applied to blob.reload(), if a reload
-        is needed during seek().
     """
 
     def __init__(self, blob, chunk_size=None, retry=DEFAULT_RETRY, **download_kwargs):
+        """docstring note that download_kwargs also used for reload()"""
         for kwarg in download_kwargs:
             if kwarg not in VALID_DOWNLOAD_KWARGS:
                 raise ValueError(