QUIC: removed "quic_mtu" directive. The directive used to set the value of the "max_udp_payload_size" transport parameter. According to RFC 9000, Section 18.2, the value specifies the size of buffer for reading incoming datagrams: This limit does act as an additional constraint on datagram size in the same way as the path MTU, but it is a property of the endpoint and not the path; see Section 14. It is expected that this is the space an endpoint dedicates to holding incoming packets. Current QUIC implementation uses the maximum possible buffer size (65527) for reading datagrams.

--- a/src/event/quic/ngx_event_quic.h
+++ b/src/event/quic/ngx_event_quic.h
@@ -69,7 +69,6 @@ typedef struct {
     ngx_flag_t                     disable_active_migration;
     ngx_msec_t                     timeout;
     ngx_str_t                      host_key;
-    size_t                         mtu;
     size_t                         stream_buffer_size;
     ngx_uint_t                     max_concurrent_streams_bidi;
     ngx_uint_t                     max_concurrent_streams_uni;