test: make test-tls-invoke-queued use public API

`parallel/test-tls-invoke-queued` previously used the internal
`_write()` API to hook into the internals more directly, but this
invalidates the general assumption made by streams APIs that
only a single write is active at a time, and which is enforced
through the public API.

PR-URL: https://github.com/nodejs/node/pull/17864


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>