Changes to Moving Average REST API

[codebrain]

Seen: https://github.com/elastic/elasticsearch-net/pull/4503/checks?check_run_id=538335701

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Tests.Aggregations.Pipeline.MovingAverage.MovingAverageHoltLinearAggregationUsageTests.ReturnsExpectedResponse
Tests.Framework.EndpointTests.ResponseAssertionException : Expected response.IsValid to be true because Invalid NEST response built from a unsuccessful (400) low level call on POST: /project/_search?pretty=true&error_trace=true&typed_keys=true
# Server indicated deprecations:
- 299 Elasticsearch-7.7.0-8fab26ad3a536257194c2b55b48064f51de55dc3 "The moving_avg aggregation has been deprecated in favor of the moving_fn aggregation."
- 299 Elasticsearch-7.7.0-8fab26ad3a536257194c2b55b48064f51de55dc3 "[interval] on [date_histogram] is deprecated, use [fixed_interval] or [calendar_interval] in the future."
# Audit trail of this API call:
 - [1] BadResponse: Node: http://localhost:9200/ Took: 00:00:00.0633842

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Tests.Cluster.NodesInfo.NodesInfoApiTests.ReturnsExpectedStatusCode
Elasticsearch.Net.UnexpectedElasticsearchClientException : Requested value 'transform' was not found.
---- System.ArgumentException : Requested value 'transform' was not found.

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Tests.Aggregations.Pipeline.MovingAverage.MovingAverageEwmaAggregationUsageTests.ReturnsExpectedStatusCode
Tests.Framework.EndpointTests.ResponseAssertionException : Expected response.IsValid to be true because Invalid NEST response built from a unsuccessful (400) low level call on POST: /project/_search?pretty=true&error_trace=true&typed_keys=true
# Server indicated deprecations:
- 299 Elasticsearch-7.7.0-8fab26ad3a536257194c2b55b48064f51de55dc3 "The moving_avg aggregation has been deprecated in favor of the moving_fn aggregation."
- 299 Elasticsearch-7.7.0-8fab26ad3a536257194c2b55b48064f51de55dc3 "[interval] on [date_histogram] is deprecated, use [fixed_interval] or [calendar_interval] in the future."
# Audit trail of this API call:
 - [1] BadResponse: Node: http://localhost:9200/ Took: 00:00:00.0136357
# OriginalException: Elasticsearch.Net.ElasticsearchClientException: Request failed to execute. Call: Status code 400 from: POST /project/_search?pretty=true&error_trace=true&typed_keys=true. ServerError: Type: action_request_validation_exception Reason: "Validation Failed: 1: parent histogram of moving_avg aggregation [commits_moving_avg] must have min_doc_count of 0;"

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Tests.Aggregations.Pipeline.MovingAverage.MovingAverageHoltWintersUsageTests.ReturnsExpectedIsValid
Tests.Framework.EndpointTests.ResponseAssertionException : Expected response.IsValid to be True because Invalid NEST response built from a unsuccessful (400) low level call on POST: /project/_search?pretty=true&error_trace=true&typed_keys=true
# Server indicated deprecations:
- 299 Elasticsearch-7.7.0-8fab26ad3a536257194c2b55b48064f51de55dc3 "The moving_avg aggregation has been deprecated in favor of the moving_fn aggregation."
- 299 Elasticsearch-7.7.0-8fab26ad3a536257194c2b55b48064f51de55dc3 "[interval] on [date_histogram] is deprecated, use [fixed_interval] or [calendar_interval] in the future."
# Audit trail of this API call:
 - [1] BadResponse: Node: http://localhost:9200/ Took: 00:00:00.1229980
# OriginalException: Elasticsearch.Net.ElasticsearchClientException: Request failed to execute. Call: Status code 400 from: POST /project/_search?pretty=true&error_trace=true&typed_keys=true. ServerError: Type: action_request_validation_exception Reason: "Validation Failed: 1: parent histogram of moving_avg aggregation [commits_moving_avg] must have min_doc_count of 0;"