[release]: skip executed stages (elastic#2261)

Author: v1v

.ci/release/Jenkinsfile

@@ -94,6 +94,9 @@ pipeline {
           }
         }
         stage('Require confirmation that CHANGELOG.asciidoc has been updated') {
+          when {
+            expression { return false }
+          }
           steps {
             input(message: """
             Update CHANGELOG.asciidoc to reflect the new version release:
@@ -109,6 +112,9 @@ pipeline {
           }
         }
         stage('Set release version') {
+          when {
+            expression { return false }
+          }
           steps {
             dir("${BASE_DIR}"){
               script {
@@ -138,13 +144,19 @@ pipeline {
           }
         }
         stage('Wait on internal CI') {
+          when {
+            expression { return false }
+          }
           steps {
             notifyStatus(slackStatus: 'warning', subject: "[${env.REPO}] Release ready to be pushed",
                           body: "Please go to (<${env.BUILD_URL}input|here>) to approve or reject within 12 hours.")
             input(message: "Start the release job on the internal CI. Click 'Proceed' once the job has succeeded or click 'Abort' if the release has failed and then manually undo the release.")
           }
         }
         stage('Nexus release') {
+          when {
+            expression { return false }
+          }
           steps {
             notifyStatus(slackStatus: 'warning', subject: "[${env.REPO}] Release ready to be published in Nexus",
                          body: "Please go to (<https://oss.sonatype.org/|here>) to proceed with the manual nexus release. Login details in LastPass")