[bug fix] validate lower bound for top n size

[ansjcy]

Description

Currently the top n size can be set to a negative number. We want to limit top size between 1 and QueryInsightsSettings.MAX_N_SIZE.

curl -X PUT 'localhost:9200/_cluster/settings' -H 'Content-Type: application/json' -d'
{
    "persistent" : {
        "search.insights.top_queries.latency.top_n_size" : -1
    }
}'
{"error":{"root_cause":[{"type":"illegal_argument_exception","reason":"illegal value can't update [search.insights.top_queries.latency.top_n_size] from [3] to [-1]"}],"type":"illegal_argument_exception","reason":"illegal value can't update [search.insights.top_queries.latency.top_n_size] from [3] to [-1]","caused_by":{"type":"illegal_argument_exception","reason":"Top N size setting for [latency] should be between 1 and 100, was (-1)"}},"status":400}

Check List

• [x] Functionality includes testing.
• [ ] API changes companion pull request created, if applicable.
• [ ] Public documentation issue/PR created, if applicable.

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