tls: reset secureConnecting on client socket

secureConnecting is never set to false on client TLS sockets.
So if Http2Session constructor (in lib/internal/http2/core.js) is
called after secureConnect is emitted, then it will wrongly wait
for a secureConnect event.

This fix sets secureConnecting to false when a client TLS socket
has connected.

PR-URL: https://github.com/nodejs/node/pull/33209


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>