Minor cleanup in favor of Java 16

- Addressing a few command deprecations during the major release superseded by toggles
- Don't swallow SQL warnings in loggers behind debug, as it's often set to false
- Deleted JavaVersionCheck, it's part of ServerLib.

Bukkit/src/main/java/com/plotsquared/bukkit/managers/MultiverseWorldManager.java

@@ -34,7 +34,10 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 /**
  * Multiverse specific manager that informs Multiverse of
  * world creation by executing a console command
+ * @deprecated Deprecated and scheduled for removal without replacement
+ * in favor of the build in setup wizard.
  */
+@Deprecated
 @Singleton
 public class MultiverseWorldManager extends BukkitWorldManager {