Update Elasticsearch client for 6.0 #4661
Description
In Elasticsearch 6.0, the query response objects no longer contain the boolean created and found fields. See elastic/elasticsearch#25516
command [go test -race -tags integration -cover -coverprofile /tmp/gotestcover-175921078 github.com/elastic/beats/libbeat/outputs/elasticsearch]: exit status 1
--- FAIL: TestIndex (0.31s)
api_integration_test.go:40: Index() fails: {"ok":false,"_index":"beats-test-index-11638","_type":"test","_id":"1","_source":null,"_version":1,"found":false,"exists":false,"created":false,"acknowledged":false,"matches":null}
--- FAIL: TestIngest (0.34s)
api_integration_test.go:107: Ingest() fails: {"ok":false,"_index":"beats-test-ingest-11638","_type":"test","_id":"1","_source":null,"_version":1,"found":false,"exists":false,"created":false,"acknowledged":false,"matches":null}
FAIL
coverage: 62.7% of statements