Edit chunk shall update instead of insert it (#3709)

### What problem does this PR solve?

Edit chunk shall update instead of insert it. Close #3679 

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/utils/es_conn.py

@@ -85,6 +85,9 @@ class ESConnection(DocStoreConnection):
             logging.exception("ESConnection.createIndex error %s" % (indexName))
 
     def deleteIdx(self, indexName: str, knowledgebaseId: str):
+        if len(knowledgebaseId) > 0:
+            # The index need to be alive after any kb deletion since all kb under this tenant are in one index.
+            return
         try:
             self.es.indices.delete(index=indexName, allow_no_indices=True)
         except NotFoundError:
@@ -400,7 +403,7 @@ class ESConnection(DocStoreConnection):
             if not hlts:
                 continue
             txt = "...".join([a for a in list(hlts.items())[0][1]])
-            if not is_english(txt.split(" ")):
+            if not is_english(txt.split()):
                 ans[d["_id"]] = txt
                 continue