tls: make StreamWrap work correctly in "drain" callback

When an instance of StreamWrap is shutting down and a "drain" event
is emitted, the instance will abort as its
`this[kCurrentShutdownRequest]` is already set. The following test
will fail before this commit.

PR-URL: https://github.com/nodejs/node/pull/23294


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>