Fix plugin loggers on server shutdown

paper-server/src/main/java/io/papermc/paper/log/CustomLogManager.java

@@ -0,0 +1,26 @@
+package io.papermc.paper.log;
+
+import java.util.logging.LogManager;
+
+public class CustomLogManager extends LogManager {
+    private static CustomLogManager instance;
+
+    public CustomLogManager() {
+        instance = this;
+    }
+
+    @Override
+    public void reset() {
+        // Ignore calls to this method
+    }
+
+    private void superReset() {
+        super.reset();
+    }
+
+    public static void forceReset() {
+        if (instance != null) {
+            instance.superReset();
+        }
+    }
+}