when we're not using blocking, just go direct to the database

related to discussion around #707

This seems right for sequences. I'm not sure about tables though.

Author: gavinking

hibernate-reactive-core/src/main/java/org/hibernate/reactive/id/impl/BlockingIdentifierGenerator.java

@@ -54,6 +54,11 @@ protected synchronized long next(long hi) {
 
     @Override
     public CompletionStage<Long> generate(ReactiveConnectionSupplier session, Object entity) {
+        if ( getBlockSize()<=1 ) {
+            //special case where we're not using blocking at all
+            return nextHiValue(session);
+        }
+
         long local = next();
         if ( local >= 0 ) {
             // We don't need to update or initialize the hi