Update PhabricatorLiskDAO::chunkSQL() for new %Q semantics

Summary:
Ref T13217. This method is slightly tricky:

• We can't safely return a string: return an array instead.
• It no longer makes sense to accept glue. All callers use ', ' as glue anyway, so hard-code that.

Then convert all callsites.

Test Plan: Browsed around, saw fewer "unsafe" errors in error log.

Reviewers: amckinley

Reviewed By: amckinley

Subscribers: yelirekim, PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13217

Differential Revision: https://secure.phabricator.com/D19784