Remove 'listener.wss.external.handshake_timeout' for cowboy does not support this option

etc/acl.conf

@@ -24,3 +24,4 @@
 
 {deny, all, subscribe, ["$SYS/#", {eq, "#"}]}.
 
+{allow, all}.

etc/emqx.conf

@@ -1160,13 +1160,6 @@ listener.wss.external.verify_protocol_header = on
 ## Value: String, seperated by ','
 ## listener.wss.external.tls_versions = tlsv1.2,tlsv1.1,tlsv1
 
-## TLS Handshake timeout.
-##
-## See: listener.ssl.$name.handshake_timeout
-##
-## Value: Duration
-listener.wss.external.handshake_timeout = 15s
-
 ## Path to the file containing the user's private PEM-encoded key.
 ##
 ## See: listener.ssl.$name.keyfile

priv/emqx.schema

@@ -989,10 +989,10 @@ end}.
   {datatype, {duration, ms}}
 ]}.
 
-{mapping, "listener.wss.$name.handshake_timeout", "emqx.listeners", [
-  {default, "15s"},
-  {datatype, {duration, ms}}
-]}.
+%%{mapping, "listener.wss.$name.handshake_timeout", "emqx.listeners", [
+%%  {default, "15s"},
+%%  {datatype, {duration, ms}}
+%%]}.
 
 {mapping, "listener.wss.$name.backlog", "emqx.listeners", [
   {default, 1024},