gh-111798: Use lower Py_C_RECURSION_LIMIT in debug mode (#112124)

* Run again test_ast_recursion_limit() on WASI platform.
* Add _testinternalcapi.get_c_recursion_remaining().
* Fix test_ast and test_sys_settrace: test_ast_recursion_limit() and
  test_trace_unpack_long_sequence() now adjust the maximum recursion
  depth depending on the the remaining C recursion.