Revert back checking on handshake messages length

Revert back checking on handshake messages length due to
limitation on our fragmentation support of handshake
messages.

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index c6ae2ca..8fd295f 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -4883,8 +4883,7 @@
 
 # Currently test certificates being used do not fit in 513 record size limit
 # so 513 record size limit tests will not pass until certificates size
-# is reduced.
-# TODO: use smaller certificates in during MbedTLS TLS 1.3 server testing.
+# is reduced or handshake messages fragmentation is supported.
 
 # requires_gnutls_tls1_3
 # requires_gnutls_record_size_limit