test: include file mode in assert message

If the REPL history file is created with an invalid mode include
the failed mode in the error message.

PR-URL: https://github.com/nodejs/node/pull/16815


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>