[3.13] gh-137400: Fix thread-safety issues when profiling all threads (gh-137518) (gh-137733)

There were a few thread-safety issues when profiling or tracing all
threads via PyEval_SetProfileAllThreads or PyEval_SetTraceAllThreads:

* The loop over thread states could crash if a thread exits concurrently
  (in both the free threading and default build)
* The modification of `c_profilefunc` and `c_tracefunc` wasn't
  thread-safe on the free threading build.
(cherry picked from commit a10152f8fd)

Lib/test/test_free_threading/test_monitoring.py

@@ -193,6 +193,32 @@ def during_threads(self):
         self.set = not self.set
 
 
+@threading_helper.requires_working_threading()
+class SetProfileAllThreadsMultiThreaded(InstrumentationMultiThreadedMixin, TestCase):
+    """Uses threading.setprofile_all_threads and repeatedly toggles instrumentation on and off"""
+
+    def setUp(self):
+        self.set = False
+        self.called = False
+
+    def after_test(self):
+        self.assertTrue(self.called)
+
+    def tearDown(self):
+        threading.setprofile_all_threads(None)
+
+    def trace_func(self, frame, event, arg):
+        self.called = True
+        return self.trace_func
+
+    def during_threads(self):
+        if self.set:
+            threading.setprofile_all_threads(self.trace_func)
+        else:
+            threading.setprofile_all_threads(None)
+        self.set = not self.set
+
+
 @threading_helper.requires_working_threading()
 class SetProfileAllMultiThreaded(TestCase):
     def test_profile_all_threads(self):