CLEANUP: quic: Missing succesful SSL handshake backend trace (OpenSSL 3.5)

CLEANUP: quic: Missing succesful SSL handshake backend trace (OpenSSL 3.5)

This very minor issue impacts only the backend when compiled against OpenSSL 3.5
with QUIC API (HAVE_OPENSSL_QUIC).

The "SSL handshake OK" trace was not dumped by a TRACE() call. This was very
annoying when debugging.

Modify the concerned code section which is a bit ugly and simplify it.
The TRACE() call is done at a unique location for now on.

Should be backported to 3.2 to ease any further backport.