multiprocessing.Pool: leak of global named resources using multiprocessing spawn

Bug report

Bug description:

I'm receiving a warning when using the multiprocessing.Pool in spawn mode.

/opt/pyenv/versions/3.12.4/lib/python3.12/multiprocessing/resource_tracker.py:254: UserWarning: resource_tracker: There appear to be 1 leaked semaphore objects to clean up at shutdown
  warnings.warn('resource_tracker: There appear to be %d '

A similar issue was brought up and fixed before, when multiprocessing.Process was used:
https://github.com/python/cpython/pull/30617

The test case introduced by the PR above: https://github.com/python/cpython/blob/3.12/Lib/test/_test_multiprocessing.py#L6040C7-L6040C24

To trigger the warning, I just replaced the Process with Pool as follows:

import multiprocessing as mp
ctx = mp.get_context('spawn')
global_resource = ctx.Semaphore()
def submain(): pass
if __name__ == '__main__':
    p = ctx.Pool(processes=3).starmap(submain, [tuple() for i in range(5)])

CPython versions tested on:

3.11, 3.12, CPython main branch

Operating systems tested on:

Linux

从报告中展示的 multiprocessing 资源跟踪行为开始，并将 PR 30617 中现有的 Process 修复与 Pool 处理进行比较。以 Lib/test/_test_multiprocessing.py 中引用的回归测试为起点，然后在 Linux 上重现 spawn-mode Pool 示例。完成的标准是该示例不再报告泄漏的信号量，并且该行为由回归测试覆盖。