Mark some tests `test_cmd_line` as `cpython_only`

[sobolevn]

Bug report

There are different tests that are skipped due to various reasons (like exact --help output matches or malloc usages, frozen imports, etc) on other implementations. For example, RustPython: https://github.com/RustPython/RustPython/blob/92c8b371ae5db0d95bd8199bc42b08af115bb88a/Lib/test/test_cmd_line.py

Take note that some skips look more like bugs / incomplete features in RustPython, however it is better to mark some tests that we can be sure as CPython-only.

I have a PR ready with the full description of each case.

Linked PRs

• gh-116858: Add @cpython_only to several tests in test_cmd_line #116859
• [3.12] gh-116858: Add @cpython_only to several tests in test_cmd_line (GH-116859) #116889
• [3.11] gh-116858: Add @cpython_only to several tests in test_cmd_line (GH-116859) #116890

[Eclips4]

FYI, there's already a similiar meta issue: #115142