Do not remove plugin chunk tickets on shutdown

The chunk system may not be responsive in a shutdown (i.e
watchdog timeout). Therefore, we should avoid interacting
with the chunk system to increase the odds of a graceful
shutdown.

paper-server/src/main/java/io/papermc/paper/plugin/manager/PaperPluginInstanceManager.java

@@ -311,8 +311,10 @@ class PaperPluginInstanceManager {
         }
 
         try {
-            for (World world : this.server.getWorlds()) {
-                world.removePluginChunkTickets(plugin);
+            if (!this.server.isStopping()) {
+                for (World world : this.server.getWorlds()) {
+                    world.removePluginChunkTickets(plugin);
+                }
             }
         } catch (Throwable ex) {
             this.handlePluginException("Error occurred (in the plugin loader) while removing chunk tickets for " + pluginName + " (Is it up to date?)", ex, plugin); // Paper