Fix the memory of shutdown policy too_large (#3168)

etc/emqx.conf

@@ -825,7 +825,7 @@ zone.internal.enable_flapping_detect = off
 ## Default:
 ##   - 10000|32MB on ARCH_64 system
 ##   - 10000|16MB on ARCH_32 sytem
-zone.internal.force_shutdown_policy = 100000|256MB
+zone.internal.force_shutdown_policy = 100000|64MB
 
 ## All the topics will be prefixed with the mountpoint path if this option is enabled.
 ##