fix: grpc_set_header Te trailers (#9312)

Author: AstarLight

apisix/cli/ngx_tpl.lua

@@ -766,6 +766,7 @@ http {
             grpc_set_header   "Host" $upstream_host;
             {% end %}
             grpc_set_header   Content-Type application/grpc;
+            grpc_set_header   TE trailers;
             grpc_socket_keepalive on;
             grpc_pass         $upstream_scheme://apisix_backend;
 

t/APISIX.pm

@@ -203,6 +203,7 @@ _EOC_
 
 $grpc_location .= <<_EOC_;
             grpc_set_header   Content-Type application/grpc;
+            grpc_set_header   TE trailers;
             grpc_socket_keepalive on;
             grpc_pass         \$upstream_scheme://apisix_backend;