1. One case with subobjects:false doesn't work as hoped:

// this does NOT return an error - it just silently "fails" to create the _project entry
PUT test333?error_trace=true
{
   "mappings": {
     "subobjects": false,
     "properties" : {
      "_project" : {
        "type" : "object"
      }
    }
  }
}

// YAY - this one fails with correct error message
PUT test333?error_trace=true
{
  "mappings": {
    "subobjects": false,
    "properties": {
      "_project": {
        "type": "object",
        "properties": {
          "myfield": {
            "type": "keyword"
          }
        }
      }
    }
  }
}

2. Creating a runtime mapping is not detected and prevented:

PUT /rt-index
{
  "mappings": {
    "runtime": {
      "_project": {
        "type": "keyword",
        "script": {
          "source": "emit(doc['existing_field'].value + ' some additional text')"
        }
      }
    }
  }
}

…ected - basic manual tests now pass

…ssField can call it without a Mapper reference

This prevents _project or _project.foo mappings in query-time runtime mappings.

For example, these now fail with "Mapping rejected: [_project.foo]. No mappings of [_project] are allowed in order to avoid conflicts with project metadata tags in serverless"
GET /blogs/_search
{
  "runtime_mappings": {
    "_project": {
      "type": "keyword",
      "script": {
        "source": "emit('somevalue')"
      }
    }
  },
  "query": {
    "match_all": {}
  },
  "fields": ["_project"]
}

GET /blogs/_search
{
  "runtime_mappings": {
    "_project.foo": {
      "type": "keyword",
      "script": {
        "source": "emit('somevalue')"
      }
    }
  },
  "query": {
    "match_all": {}
  },
  "fields": ["_project.foo"]
}

…d.parseRuntimeFields.

Removed checks from RootObjectMapper and IndexService.
This checks both query-time and index-time runtime field mappings.

…lidate

…ime; no query time runtime mapping tests

…lidator

…it-_project-mappings

…it-_project-mappings

…it-_project-mappings

…it-_project-mappings

…it-_project-mappings