[Fix] Increased database clean task start delay

1 second delay is not enough when a patch system has not applied all
patches, and some data requiring patching is scheduled for removal.

Affected issues: #732

Plan/src/main/java/com/djrapitops/plan/system/database/DBSystem.java

@@ -81,7 +81,7 @@ public abstract class DBSystem implements SubSystem {
         try {
             Benchmark.start("Init Database");
             initDatabase();
-            db.scheduleClean(1L);
+            db.scheduleClean(20L);
             Log.info(locale.get().getString(PluginLang.ENABLED_DATABASE, db.getName()));
             Benchmark.stop("Enable", "Init Database");
         } catch (DBInitException e) {