Fix additional "xsprintf()"-family static parameter errors

Summary:
Ref T13577. After the lint rule fix in D21453, it can identify more errors. Fix the errors it identifies in "arcanist/".

These all seem fairly obscure/benign.

Test Plan: Ran arc lint on the files before and after these changes. Did not specifically re-test these particular messages, but they mostly very obscure.

Maniphest Tasks: T13577

Differential Revision: https://secure.phabricator.com/D21456