Fix more "msort()" vs "msortv()" callsites

Summary:
See https://discourse.phabricator-community.org/t/unhandled-exception-when-logging-in-with-mfa/2828. The recent changes to turn msort() on a vector an error have smoked out a few more of these mistakes.

These cases do not meaningfully rely on sort stability so there's no real bug being fixed, but we'd still prefer msortv().

Test Plan: Viewed MFA and External Account settings panels. Did a git grep 'msort(' | grep -i vector for any more obvious callsites, but none turned up.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20587