fix(authz): authz http pool_type use default value `random`

apps/emqx_authz/src/emqx_authz_http.erl

@@ -105,6 +105,8 @@ parse_config(#{ url := URL
                                      ?PLACEHOLDERS)
          , headers              => Headers
          , request_timeout      => ReqTimeout
+           %% pool_type default value `random`
+         , pool_type            => random
          }.
 
 parse_fullpath(RawURL) ->

apps/emqx_authz/src/emqx_authz_schema.erl

@@ -146,7 +146,9 @@ http_common_fields() ->
     [ {url, fun url/1}
     , {request_timeout, mk_duration("Request timeout", #{default => "30s"})}
     , {body, #{type => map(), nullable => true}}
-    ] ++ proplists:delete(base_url, connector_fields(http)).
+    ] ++ maps:to_list(maps:without([ base_url
+                                   , pool_type],
+                                   maps:from_list(connector_fields(http)))).
 
 mongo_common_fields() ->
     [ {collection, #{type => atom()}}