Correct bin/storage analyze internal API for cluster environments

Summary:
Ref T12819. This worked right in a non-cluster environment, but bin/storage upgrade iterates over each master in a partitioned cluster environment.

Tweak the API so bin/storage analyze targets a single host but bin/storage upgrade can hit all the masters.

Test Plan: Will run bin/storage upgrade in production again. Ran upgrade and analyze locally, still work fine.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12819

Differential Revision: https://secure.phabricator.com/D18576