MINOR: quic: Remove a useless test about probing in qc_prep_pkts()

qel->pktns->tx.pto_probe is set to 0 after having prepared a probing
datagram. There is no reason to check this parameter. Furthermore
it is always 0 when the connection does not probe the peer.

Must be backported to 2.6 and 2.7.
diff --git a/src/quic_conn.c b/src/quic_conn.c
index 8e7f21d..95ba744 100644
--- a/src/quic_conn.c
+++ b/src/quic_conn.c
@@ -3675,7 +3675,7 @@
 		 * select the next level.
 		 */
 		if ((tel == QUIC_TLS_ENC_LEVEL_INITIAL || tel == QUIC_TLS_ENC_LEVEL_HANDSHAKE) &&
-		    next_tel != QUIC_TLS_ENC_LEVEL_NONE && (LIST_ISEMPTY(frms) && !qel->pktns->tx.pto_probe)) {
+		    next_tel != QUIC_TLS_ENC_LEVEL_NONE && (LIST_ISEMPTY(frms))) {
 			/* If QUIC_TLS_ENC_LEVEL_HANDSHAKE was already reached let's try QUIC_TLS_ENC_LEVEL_APP */
 			if (tel == QUIC_TLS_ENC_LEVEL_HANDSHAKE && next_tel == tel)
 				next_tel = QUIC_TLS_ENC_LEVEL_APP;