Too wide location info for CHECK_EG_MATCH

The line number of the instructions emitted for except* (CHECK_EG_MATCH etc) spans the entire except* body, and this shows up in the traceback when except* raises (e.g. when split() fails).

>>> class Bad(ExceptionGroup):
...     def split(*args):
...         1/0
...         
>>> try: raise Bad("", [ValueError(), TypeError()])
... except* ValueError:
...     1
...     2
...     3
...     
  + Exception Group Traceback (most recent call last):
  |   File "<python-input-1>", line 1, in <module>
  |     try: raise Bad("", [ValueError(), TypeError()])
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  | Bad:  (2 sub-exceptions)
  +-+---------------- 1 ----------------
    | ValueError
    +---------------- 2 ----------------
    | TypeError
    +------------------------------------

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<python-input-1>", line 2, in <module>
    except* ValueError:
    ...<2 lines>...
        3
  File "<python-input-0>", line 3, in split
    1/0
    ~^~
ZeroDivisionError: division by zero

Linked PRs

• gh-129026

使用 issue 中的 except* 和 Bad.split() 示例重现 traceback，然后检查链接的 PR gh-129026 以了解实现背景。当 CHECK_EG_MATCH 位置不再覆盖整个 except* 主体，且显示的 traceback 仍然正确时，即表示完成。