R1:7d9bda59a6bf

Prevent worker queue leases from exceeding 64 characters

Summary:
Ref T6742. Root cause of the issue:

- Daemon was running on a machine with a very long host name, which produced a lease name which was longer than 64 characters.
- MySQL wasn't set in STRICT_ALL_TABLES.
- The daemon would `UPDATE .. SET leaseOwner = <very long string>` to lock a task, and MySQL would silently truncate.
- The daemon would then try to select the locked task, but fail, because there's no matching lease owner.

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