Auto merge of #12657 - asajeffrey:panic-backtrace-println, r=nox

Print backtraces for panics, even if the constellation has closed.

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At the moment, threads rely on the constellation to print out the reason for a panic, so panics that happen after the constellation closes are dropped on the floor. cc @jdm

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12626
- [X] These changes do not require tests because they are fixing panic behaviour

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