make term similarity robust (#2212)

### What problem does this PR solve?


### Type of change

- [x] Performance Improvement

rag/nlp/query.py

@@ -106,10 +106,9 @@ class EsQueryer:
                         m) for m in sm]
                 sm = [EsQueryer.subSpecialChar(m) for m in sm if len(m) > 1]
                 sm = [m for m in sm if len(m) > 1]
-                if len(sm) < 2:
-                    sm = []
 
                 keywords.append(re.sub(r"[ \\\"']+", "", tk))
+                keywords.extend(sm)
                 if len(keywords) >= 12: break
 
                 tk_syns = self.syn.lookup(tk)