[BUG] system limit from `plugins.ppl.join.subsearch_maxout` prevents sort push down for sort merge join

[qianheng-aws]

What is the bug?
system limit from plugins.ppl.join.subsearch_maxout prevents sort push down for sort merge join

How can one reproduce the bug?

1. Create a index, e.g.:

PUT localhost:9200/test
{
    "mappings": {
        "properties": {
            "id": {
                "type": "text"
            },
            "value": {
                "type": "integer"
            }
        }
    }
}

2. explain the physical plan for a join query:

POST localhost:9200/_plugins/_ppl/_explain?format=extended

source=test | join value test 

and get final plan:

...
EnumerableCalc(expr#0..2=[{inputs}], value=[$t1], id=[$t2])
  EnumerableLimit(fetch=[10000])
    EnumerableMergeJoin(condition=[=($0, $1)], joinType=[inner])
      CalciteEnumerableIndexScan(table=[[OpenSearch, test]], PushDownContext=[[PROJECT->[value], SORT->[{\"value\" : {\"order\" : \"asc\",\"missing\" : \"_last\"}]], OpenSearchRequestBuilder(sourceBuilder={\"from\":0,\"timeout\":\"1m\",\"_source\":{\"includes\":[\"value\"],\"excludes\":[]},\"sort\":[{\"value\":{\"order\":\"asc\",\"missing\":\"_last\"}}]}, requestedTotalSize=2147483647, pageSize=null, startFrom=0)])
      EnumerableSort(sort0=[$0], dir0=[ASC])
        CalciteEnumerableIndexScan(table=[[OpenSearch, test]], PushDownContext=[[PROJECT->[value, id], LIMIT->50000], OpenSearchRequestBuilder(sourceBuilder={\"from\":0,\"size\":50000,\"timeout\":\"1m\",\"_source\":{\"includes\":[\"value\",\"id\"],\"excludes\":[]}}, requestedTotalSize=50000, pageSize=null, startFrom=0)])
...

What is the expected behavior?
The EnumerableSort operator on the right child of join should be pushed down into scan. Although there is limit pushed down before the sort, that limit is a system limit from a guard rail configuration which should not prevent sort.

What is your host/environment?

• OS: macos
• Version 3.3.0-snapshot
• Plugins

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Do you have any additional context?
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