Fix two setup issues arising from partitioning support

Summary:
Ref T11044.

• Use shorter lock names. Fixes T11916.
• These granular exceptions now always raise as a more generic "Cluster" exception, even for a single host, because there's less special code around running just one database.

Test Plan:

• Configured bad mysql.port, ran bin/storage upgrade, got a more helpful error message.
• Ran bin/storage upgrade --trace, saw shorter lock names.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11044, T11916

Differential Revision: https://secure.phabricator.com/D16924