R1:ee6e2a396fec

Fix some test suite stragglers with PHP 8.1 compatibility

Summary: Ref T13588. This allows "arc unit --everything" to more or less run cleanly on PHP 8.1.

Test Plan: Ran "arc unit --everything".

Maniphest Tasks: T13588

Differential Revision: https://secure.phabricator.com/D21821