Revert "bpo-33608: Factor out a private, per-interpreter _Py_AddPendingCall(). (gh-13714)" (GH-13780)

This reverts commit 6a150bcaeb190d1731b38ab9c7a5d1a352847ddc.
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 88bda05..43d7a08 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -431,7 +431,7 @@
     def test_pendingcalls_threaded(self):
 
         #do every callback on a separate thread
-        n = 32 #total callbacks (see NPENDINGCALLS in pycore_ceval.h)
+        n = 32 #total callbacks
         threads = []
         class foo(object):pass
         context = foo()