crypto: remove unused SSLWrap handle methods

One was not used at all, and the other was only used in a test, which I
converted to use the more standard `ShutdownWrap` API.

PR-URL: https://github.com/nodejs/node/pull/22216


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>