FSA: Fix file cleanup code in WPTs
Recently attempted to add cleanup code to these tests but the cleanup
code was incorrect. The tests continued to pass so it wasn't caught by
the CQ.
This fixes the cleanup code.
Bug: 363601806
Change-Id: Ice9f23cc1400854002c3e9b4f3a45ce11dbc0cc8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5846508
Reviewed-by: Christine Hollingsworth christinesm@chromium.org
Commit-Queue: Nathan Memmott memmott@chromium.org
Cr-Commit-Position: refs/heads/main@{#1353627}