[3.13] gh-121605: Fix test hang when pyrepl is not available (GH-121820) (GH-121823)

The fallback repl does not support "exit" without parentheses, so the
test would hang until the timeout expired.
(cherry picked from commit 4134261ab831863565fefc7a04d05a1fc1bca2f8)

Co-authored-by: Sam Gross <colesbury@gmail.com>