Extend timeout for TLSProxy

I received this error from a TLSProxy test:

Failed to start up server (localhost,4443): Transport endpoint is not
connected

So, extend the timeout before we give up trying to connect to the server.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5088)

(cherry picked from commit 82992a41)