domain: remove `.dispose()`

domain.dispose() is generally considered an anti-pattern, has been runtime-deprecated for over 4 years, and is a part of the domain module that can not be emulated by async_hooks; so remove it.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

domain

/cc @trevnorris