test: add github refs to flaky tests
See https://github.com/nodejs/reliability/issues/1, I'm trying to get the info on flakes correct.
I also adjusted platform labels for the issues, though that can't be seen in this PR, and added a platform label for Linux, since one was missing and there were some Linux flakes.
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines