subprocess.run timeout does not function if shell=True and capture_output=True

Bug report

Bug description:

I am using python 3.12.4 on windows 10 and when calling subprocess.run("powershell", shell=True, capture_output=True, timeout=1) code execution seems to suspend indefinetly as the process now accepts the user input and interprets it.

This behaviour matches the one described in #81605 despite it having supposedly been fixed 5 years ago.
For example when calling subprocess.run("cmd", shell=True, capture_output=True, timeout=1) and then entering echo o>f.txt a new file called "f.txt" gets created with "o" as its content.

When using the IDLE Shell the process completes nearly instandly and returns this:

CompletedProcess(args='powershell', returncode=0, stdout=b'Windows PowerShell\r\nCopyright (C) Microsoft Corporation. Alle Rechte vorbehalten.\r\n\r\nLernen Sie das neue plattform\x81bergreifende PowerShell kennen - https://aka.ms/pscore6\r\n\r\nPS C:\Users\Mabeeck\Desktop\Python> ', stderr=b'')

The same applies for Python 3.8.9, 3.9.2, 3.10.6, 3.11.5 and 3.13.0b3
I'll apoligise in advance, if my impression of the bug beeing supposed to be fixed is wrong.

CPython versions tested on:

3.8, 3.9, 3.10, 3.11, 3.12, 3.13

Operating systems tested on:

Windows

Windows で shell=True、capture_output=True、timeout=1 を指定した subprocess.run エントリポイントから始め、報告された powershell と cmd のケースを再現します。記載されている Python バージョン間で挙動を比較し、子プロセスが入力を受け付ける場合にどのような timeout の挙動になるべきかを判断します。無期限の停止が解消され、その挙動が適切な回帰テストでカバーされた時点で issue は完了です。