Revert "Destroy test VMs on clean (#28818)"

This reverts commit f66234bdd5.

buildSrc/src/main/groovy/org/elasticsearch/gradle/vagrant/VagrantTestPlugin.groovy

@@ -258,9 +258,6 @@ class VagrantTestPlugin implements Plugin<Project> {
     private static void createVagrantBoxesTasks(Project project) {
         assert project.extensions.esvagrant.boxes != null
 
-        final Task clean = project.tasks.clean
-        assert clean != null
-
         assert project.tasks.stop != null
         Task stop = project.tasks.stop
 
@@ -337,7 +334,6 @@ class VagrantTestPlugin implements Plugin<Project> {
             }
             destroy.onlyIf { vagrantDestroy }
             update.mustRunAfter(destroy)
-            clean.dependsOn(destroy)
 
             Task up = project.tasks.create("vagrant${boxTask}#up", VagrantCommandTask) {
                 command 'up'