remove database auto purge methods

src/main/java/fr/xephi/authme/datasource/CacheDataSource.java

@@ -138,16 +138,6 @@ public class CacheDataSource implements DataSource {
         return result;
     }
 
-    @Override
-    public Set<String> autoPurgeDatabase(long until) {
-        Set<String> cleared = source.autoPurgeDatabase(until);
-        for (String name : cleared) {
-            cachedAuths.invalidate(name);
-        }
-
-        return cleared;
-    }
-
     @Override
     public Set<String> getRecordsToPurge(long until) {
         return source.getRecordsToPurge(until);