PLT-7862: Support batched live indexing. (#7640)

config/default.json

@@ -316,7 +316,8 @@
         "PostIndexShards": 1,
         "AggregatePostsAfterDays": 365,
         "PostsAggregatorJobStartTime": "03:00",
-        "IndexPrefix": ""
+        "IndexPrefix": "",
+        "LiveIndexingBatchSize": 1
     },
     "DataRetentionSettings": {
         "EnableMessageDeletion": false,