[3.14] gh-152682: Fix NULL dereference on OOM in `symtable_visit_type_param_bound_or_...

[3.14] gh-152682: Fix NULL dereference on OOM in `symtable_visit_type_param_bound_or_default` (GH-152684) (#152696)

In `symtable_visit_type_param_bound_or_default()`, when a reserved name
(e.g. `__classdict__`) is used as a type parameter, `PyUnicode_FromFormat()`
is called to build the SyntaxError message. If the allocation fails and
returns NULL, the subsequent `PyErr_SetObject()` and `Py_DECREF()` calls
would dereference NULL, causing a segfault.

Fix by returning 0 immediately when `PyUnicode_FromFormat()` returns NULL.
This propagates the MemoryError set by `PyUnicode_FromFormat()`.

The bug was introduced in gh-128632 (commit 891c61c).
(cherry picked from commit 10ed03edf128ed1101ab8d04bcd715f2033fec55)

Co-authored-by: Petr Vaganov <petrvaganoff@gmail.com>
* Remove test

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Co-authored-by: Petr Vaganov <petrvaganoff@gmail.com>
Co-authored-by: Stan Ulbrych <stan@python.org>