Fix reference to cloud_storage.

BUG=Bisect bot no longer works.

TBR=prasadv@chromium.org, aiolos@chromium.org

TEST=https://codereview.chromium.org/1177623004

Review URL: https://codereview.chromium.org/1169413003

Cr-Commit-Position: refs/heads/master@{#333682}

tools/auto_bisect/fetch_build.py

@@ -23,7 +23,7 @@ import sys
 import zipfile
 
 # Telemetry (src/tools/telemetry) is expected to be in the PYTHONPATH.
-from telemetry.util import cloud_storage
+from catapult_base import cloud_storage
 
 import bisect_utils