Making Ws cleanup optional

Jenkinsfile

@@ -25,6 +25,9 @@ pipeline {
   stages {
     stage('Workspace cleanup (pre-build)') {
       steps {
+        when {
+          expression { return params.REUSE_PREV_FS == false }
+        }
         // Equivalente al PreBuildCleanup del plugin ws-cleanup
         cleanWs()
       }