test: fix flaky test-repl-sigint-nested-eval
There is a race condition where process.kill can be sent before the target is ready to receive the signal. Or at least that's what I think is going on. Regardless, objectively, using setTimeout() to slightly delay the invocation causes the test to not fail anymore using: tools/test.py --repeat=1000 test/parallel/test-repl-sigint-nested-eval