Fix RSQL filter for no target tag and OR (#1824)

* Fix RSQL filter for no target tag and OR
* add test for such filter
* Clean up the code

keeps the legacy Rsql Visitor which could be used with hawkbit.rsql.legacyRsqlVisitor=true

---------

Signed-off-by: Marinov Avgustin <Avgustin.Marinov@bosch.com>

hawkbit-repository/hawkbit-repository-api/src/main/java/org/eclipse/hawkbit/repository/rsql/RsqlConfigHolder.java

@@ -42,6 +42,10 @@ public final class RsqlConfigHolder {
     @Autowired
     private RsqlVisitorFactory rsqlVisitorFactory;
 
+    @Deprecated
+    @Value("${hawkbit.rsql.legacyRsqlVisitor:false}")
+    private boolean legacyRsqlVisitor;
+
     /**
      * @return The holder singleton instance.
      */