extend/os/linux/cleanup: use typed: strict

[p-linnane]

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Part of #17297.

[issyl0]

#18045 (comment)

[p-linnane]

@carlocab Did we want to reopen this one as well?

[Bo98]

Should be able to do it without the undef now

[p-linnane]

@dduugg knocked it out in #18056!