testsuite: mark process005 as fragile on JS

This patch marks process005 as fragile on JS, as tracked in #24373. This failure has not been addressed for a few months and occasionally still breaks marge pipelines (e.g. https://gitlab.haskell.org/ghc/ghc/-/jobs/1883299), so it should be marked as fragile before a proper fix has been delivered. cc @doyougnu @hsyl20