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

Fixes: nodejs#41123

test/parallel/test-repl-sigint-nested-eval.js

@@ -23,7 +23,7 @@ child.stdout.on('data', function(c) {
 
 child.stdout.once('data', common.mustCall(() => {
   process.on('SIGUSR2', common.mustCall(() => {
-    process.kill(child.pid, 'SIGINT');
+    setTimeout(() => { process.kill(child.pid, 'SIGINT'); }, 10);
     child.stdout.once('data', common.mustCall(() => {
       // Make sure REPL still works.
       child.stdin.end('"foobar"\n');