buffer: unconditionally use internalBinding

With the removal of test-buffer-bindingobj-no-zerofill.js,
internalBinding can be used unconditionally to assign
isAnyArrayBuffer().

PR-URL: https://github.com/nodejs/node/pull/23234
Refs: https://github.com/nodejs/node/issues/22160


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>