assert: limit string inspection when logging assertion errors

This makes sure long strings as `actual` or `expected` values on an
`AssertionError` won't be logged completely. This is important as
the actual value is somewhat redundant in combination with the error
message which already logs the difference between the input values.

PR-URL: https://github.com/nodejs/node/pull/28058


Reviewed-By: Rich Trott <rtrott@gmail.com>