fix(ext/node): cpus() should not error when there's no cpu info (#31097)
os.cpus() in Node returns an empty array if there is no cpu info. This
is also specified in [its
documentation](https://nodejs.org/api/os.html#oscpus:~:text=The%20array%20will%20be%20empty%20if%20no%20CPU%20information%20is%20available):
"The array will be empty if no CPU information is available, such as if
the /proc file system is unavailable." Currently, Deno throws an error
instead.
Fixes #25929.
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