The Profile API returns wrong results when using a global aggregation

[francoisprunier]

Elasticsearch 7.10.2 - 7.12.0

Plugins installed: []

JVM version (java -version): openjdk 11.0.10 2021-01-19

OS version Ubuntu 20.10

Description of the problem including expected versus actual behavior:
When using profile=true in REST requests, global sub aggregation results seem to be scoped by the query

Steps to reproduce:

PUT /test/_doc/1
{
  "aField": "A"
}

PUT /test/_doc/2
{
  "aField": "B"
}

PUT /test/_doc/3
{
  "aField": "B"
}

POST /test/_search
{
  "profile": "true", 
  "size":0,
  "query": {
    "term": {
      "aField.keyword": {
        "value": "B"
      }
    }
  }, 
  "aggs": {
    "aGlobal": {
      "global": {},
      "aggs": {
        "aTerm": {
          "terms": {
            "field": "aField.keyword",
            "size": 10
          }
        }
      }
    }
  }
}

It should return

(...)
"aggregations" : {
    "aGlobal" : {
      "doc_count" : 3,
      "aTerm" : {
        "doc_count_error_upper_bound" : 0,
        "sum_other_doc_count" : 0,
        "buckets" : [
          {
            "key" : "B",
            "doc_count" : 2
          },
          {
            "key" : "A",
            "doc_count" : 1
          }
        ]
      }
    }
  }
(...)

but instead we get (the only difference being "profile": "true" set in the request)

(...)
 "aggregations" : {
    "aGlobal" : {
      "doc_count" : 2,
      "aTerm" : {
        "doc_count_error_upper_bound" : 0,
        "sum_other_doc_count" : 0,
        "buckets" : [
          {
            "key" : "B",
            "doc_count" : 2
          }
        ]
      }
    }
  },
(...)

Provide logs (if relevant):

[elasticmachine]

Pinging @elastic/es-analytics-geo (Team:Analytics)

[nik9000]

I've reproduced this. It looks like its because we implement profiling by wrapping an Aggregator in one that profiles. And we implement global with an instanceof. I think this used to work because we wrapped later. But I'm not sure, I'd have to bisect to find where we broke it and I don't think that's worth it. I'll see what I can do.