fix(config): disable auto mem release by default (#411)

src/server/config.ini

@@ -236,7 +236,9 @@
   config_sync_disabled = false
   config_sync_interval_ms = 30000
 
-  mem_release_enabled = true
+  ;; WARNING: memory release may incur major performance downgrade when inproperly configured.
+  ;;          ensure this feature is only enabled when it's necessary.
+  mem_release_enabled = false
   mem_release_interval_ms = 86400000
 
   lb_interval_ms = 10000