Refine synonym query. (#3855)

### What problem does this PR solve?

### Type of change

- [x] Performance Improvement

conf/mapping.json

@@ -140,13 +140,21 @@
         }
       },
       {
-        "string": {
+        "rank_feature": {
           "match": "*_fea",
           "mapping": {
             "type": "rank_feature"
           }
         }
       },
+      {
+        "rank_features": {
+          "match": "*_feas",
+          "mapping": {
+            "type": "rank_features"
+          }
+        }
+      },
       {
         "dense_vector": {
           "match": "*_512_vec",