[3.13] gh-149590: Remove faulthandler_traverse (GH-150023) (#150087)

`faulthandler_traverse` visits Python objects owned by `_PyRuntime`, not
by the module instance. With multi-phase init allowing multiple module
instances, each instance's GC traversal decrements `gc_refs` on the same
runtime-owned objects, driving it negative when two instances are
collected simultaneously.
(cherry picked from commit 56737483c2ffdaadfec648fd38d409c6b10941c0)