test: resolve flaky repl test

[avivkeller]

Post 4f844f4 (#64034), there's a small chance that test/parallel/test-repl-user-error-handler.js will fail, since it treats our now asynchronous REPL as synchronous.

Based on the in-progress https://ci.nodejs.org/job/node-stress-single-test/800/, the flake rate is <1.5% (1 failure in 70 runs).

[avivkeller]

Actually, this looks like a bug in V8's replMode: true

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.14%. Comparing base (4f844f4) to head (1bf0e6f).

Additional details and impacted files

@@ Coverage Diff @@## main #64594 +/- ##
=======================================
Coverage 90.13% 90.14% =======================================
Files 741 741 Lines 241976 241976 Branches 45543 45551 +8 =======================================
+ Hits 218116 218126 +10 + Misses 15379 15367 -12 - Partials 8481 8483 +2 

see 36 files with indirect coverage changes

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