chore(TLS): hibernate_after default to 5s, follow version 4.x

apps/emqx/src/emqx_schema.erl

@@ -1935,8 +1935,7 @@ common_ssl_opts_schema(Defaults) ->
             sc(
                 duration(),
                 #{
-                    default => undefined,
-                    required => false,
+                    default => Df("hibernate_after", "5s"),
                     desc => ?DESC(common_ssl_opts_schema_hibernate_after)
                 }
             )}

apps/emqx/test/emqx_listeners_SUITE.erl

@@ -138,7 +138,7 @@ t_restart_listeners(_) ->
     ok = emqx_listeners:restart(),
     ok = emqx_listeners:stop().
 
-t_restart_listeners_with_hibernate_after_disabled(Config) ->
+t_restart_listeners_with_hibernate_after_disabled(_Config) ->
     OldLConf = emqx_config:get([listeners]),
     maps:foreach(
         fun(LType, Listeners) ->
@@ -154,7 +154,7 @@ t_restart_listeners_with_hibernate_after_disabled(Config) ->
                                     ssl_options,
                                     hibernate_after
                                 ],
-                                5000
+                                undefined
                             );
                         _ ->
                             skip