feat(correlation-rules): add rule_group_by_def to support grouping in correlation rules

Author: mjabascal10

backend/src/main/java/com/park/utmstack/domain/correlation/rules/UtmCorrelationRules.java

@@ -148,7 +148,7 @@ public void setDeduplicateBy(List<String> deduplicateBy) throws UtmSerialization
     private List<String> groupBy;
 
     public List<String> getGroupBy() throws UtmSerializationException {
-        if (StringUtils.hasText(deduplicateByDef))
+        if (StringUtils.hasText(ruleGroupByDef))
             groupBy = UtilSerializer.jsonDeserializeList(String.class, ruleGroupByDef);
         return groupBy == null ? new ArrayList<>() : groupBy;
     }