[BUG] Query insights tests fail on first pass

[dblock]

What is the bug?

Intermittent CI failure, e.g. https://github.com/opensearch-project/opensearch-api-specification/actions/runs/11487125212/job/31970965603?pr=637

How can one reproduce the bug?

I can reproduce it on a new docker start from tests/plugins/query_insights.

tests/plugins/query_insights $ docker compose up

npm run test:spec--insecure -- --tests tests/plugins/query_insights/insights/top_queries.yaml --verbose

        FAILED  Retrieve top queries by memory usage.
            PASSED  PARAMETERS
                PASSED  type
            PASSED  REQUEST BODY
            PASSED  RESPONSE STATUS
            PASSED  RESPONSE PAYLOAD BODY
            FAILED  RESPONSE PAYLOAD SCHEMA (data/top_queries/2/source/query/bool/adjust_pure_negative property is not defined in the spec)
            SKIPPED RESPONSE OUTPUT VALUES

Here's the response:

"top_queries": [
    {
      "timestamp": 1729713532744,
      "source": {
        "size": 10000,
        "query": {
          "bool": {
            "must_not": [
              {
                "exists": {
                  "field": "source",
                  "boost": 1
                }
              }
            ],
            "adjust_pure_negative": true,
            "boost": 1
          }
        }
      },
      "phase_latency_map": {
        "expand": 0,
        "query": 53,
        "fetch": 2
      },
      "search_type": "query_then_fetch",
      "indices": [
        ".opensearch-sap-log-types-config"
      ],
      "node_id": "G9AF1X_gQtWHg5VZjUVgtw",
      "total_shards": 1,
      "labels": {},
      "task_resource_usages": [
        {
          "action": "indices:data/read/search",
          "taskId": 43,
          "parentTaskId": -1,
          "nodeId": "G9AF1X_gQtWHg5VZjUVgtw",
          "taskResourceUsage": {
            "cpu_time_in_nanos": 1731501,
            "memory_in_bytes": 97912
          }
        }
      ],

What is the expected behavior?

Tests to pass.

Do you have any additional context?

After #625.