test: check custom inspection truncation in assert

The assert module has some truncation logic in a custom inspect
function. This was not covered in tests. Add tests to cover it.

PR-URL: https://github.com/nodejs/node/pull/28234


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>