Take crash dumps for timed-out tests.

Take crash dumps for timed-out tests.

This change updates the test infrastructure to collect crash dumps for
tests that time out. We've been seeing a number of tests that only time
out in CI (e.g. dotnet/coreclr#10076); hopefully this will help us root-cause the
timeouts.

Commit migrated from https://github.com/dotnet/coreclr/commit/6f30002fc917cdacd4d0565f05ded920ab17f830