[9.x] Fully remove Enterprise Search from Metricbeat (#42915)

* fully remove Enterprise Search from Metricbeat 9.x

* Also remove the `ent-search` monitoring index

* test ensure enterprise search directory is removed

* try full relative path; ensure removed pre-test

* be explicit about ignoring enterprisesearch tests

* remove explicit ignore; use git clean -fd

* explicitly remove directory before git clean

* ignore removed files

* add note to Changelog next

---------

Co-authored-by: Valentin Crettaz <valentin.crettaz@elastic.co>

CHANGELOG.next.asciidoc

@@ -82,6 +82,7 @@ otherwise no tag is added. {issue}42208[42208] {pull}42403[42403]
 - Add support for specifying a custom endpoint for GCP service clients. {issue}40848[40848] {pull}40918[40918]
 - Fix incorrect handling of types in SQL module. {issue}40090[40090] {pull}41607[41607]
 - Remove kibana.settings metricset since the API was removed in 8.0 {issue}30592[30592] {pull}42937[42937]
+- Removed support for the Enterprise Search module {pull}42915[42915]
 
 *Osquerybeat*
 

dev-tools/mage/module_changeset.go

@@ -91,6 +91,12 @@ func shouldIgnore(file string) bool {
 			return true
 		}
 	}
+
+	// if the file has been removed, we should ignore it
+	if _, err := os.Stat(file); os.IsNotExist(err) {
+		return true
+	}
+
 	return false
 }