Wait longer for the server in TLSProxy to start

In a recent PR (#3566) it seems that TLSProxy gave up trying to connect to
the server process too quickly. This meant the test failed even though the
server *did* eventually start. Currently we try 3 times to connect with a
0.1 second pause between each attempt. That is probably too aggressive.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3587)