gh-129825: Skip test_faulthandler.test_register_chain under TSAN

The test hangs when run under TSAN due to an interaction between TSAN's
signal interception and our attempt to call the previous signal handler.

Author: colesbury

Lib/test/test_faulthandler.py

@@ -795,6 +795,7 @@ def test_register_fd(self):
     def test_register_threads(self):
         self.check_register(all_threads=True)
 
+    @support.skip_if_sanitizer("gh-129825: hangs under TSAN", thread=True)
     def test_register_chain(self):
         self.check_register(chain=True)