src: remove unused `internalBinding('config')` properties

Remove the following properties:

- `preserveSymlinks`
- `preserveSymlinksMain`
- `experimentalModules`
- `userLoader`
- `experimentalVMModules`
- `experimentalREPLAwait`
- `exposeInternals`

We used to use them to pass cli option values from C++ into
JS, but now the values are obtained in JS land using
`require('internal/options').getOptionValue` instead so they
are unused.

Also removes `test/parallel/test-internal-modules-expose.js`
which tests `--expose-internals`.
We already have hundreds of tests depending on `--expose-internals`,
they are more than enough to test the functionality of the flag.

PR-URL: https://github.com/nodejs/node/pull/25463


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>