Remove calls to 6.x ES _xpack/* API endpoints (#18609)

* Remove guard for _xpack/monitoring endpoint

* Removing guard for _xpack/license endpoint

* Removing guard for _xpack/ml/anomaly_detectors/_all/_stats endpoint

libbeat/esleg/eslegclient/bulkapi.go

@@ -151,14 +151,7 @@ func newMonitoringBulkRequest(
 	params map[string]string,
 	body BodyEncoder,
 ) (*bulkRequest, error) {
-	var path string
-	var err error
-	if esVersion.Major < 7 {
-		path, err = makePath("_xpack", "monitoring", "_bulk")
-	} else {
-		path, err = makePath("_monitoring", "bulk", "")
-	}
-
+	path, err := makePath("_monitoring", "bulk", "")
 	if err != nil {
 		return nil, err
 	}

metricbeat/module/elasticsearch/elasticsearch.go

@@ -261,18 +261,7 @@ func GetLicense(http *helper.HTTP, resetURI string) (*License, error) {
 	}
 
 	// License not found in cache, fetch it from Elasticsearch
-	info, err := GetInfo(http, resetURI)
-	if err != nil {
-		return nil, err
-	}
-	var licensePath string
-	if info.Version.Number.Major < 7 {
-		licensePath = "_xpack/license"
-	} else {
-		licensePath = "_license"
-	}
-
-	content, err := fetchPath(http, resetURI, licensePath, "")
+	content, err := fetchPath(http, resetURI, "_license", "")
 	if err != nil {
 		return nil, err
 	}

metricbeat/module/elasticsearch/ml_job/ml_job.go

@@ -32,7 +32,7 @@ func init() {
 }
 
 const (
-	jobPathSuffix = "/anomaly_detectors/_all/_stats"
+	statsPath = "/_ml/anomaly_detectors/_all/_stats"
 )
 
 // MetricSet for ml job
@@ -44,7 +44,7 @@ type MetricSet struct {
 // any MetricSet specific configuration options if there are any.
 func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	// Get the stats from the local node
-	ms, err := elasticsearch.NewMetricSet(base, "") // servicePath will be set in Fetch() based on ES version
+	ms, err := elasticsearch.NewMetricSet(base, statsPath)
 	if err != nil {
 		return nil, err
 	}
@@ -71,12 +71,6 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 		return err
 	}
 
-	if info.Version.Number.Major < 7 {
-		m.SetServiceURI("/_xpack/ml" + jobPathSuffix)
-	} else {
-		m.SetServiceURI("/_ml" + jobPathSuffix)
-	}
-
 	content, err := m.HTTP.FetchContent()
 	if err != nil {
 		return err