test: remove flaky parallel/test-process-wrap test

It's an old test (added when switching from libev to libuv) that tests
implementation details of the internal process_wrap bindings. That kind
of thing doesn't need testing in this day and age, and since the test is
flaky, simply remove it instead of sinking time in fixing it up.

Fixes: #45805
PR-URL: #45806
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>