change stage name in jenkinsfile

api/Jenkinsfile.ble_test

@@ -26,7 +26,7 @@ pipeline {
         // ---------------------------------------------------------------------
         // 1. Build a unique screen session name, disable MOTD
         // ---------------------------------------------------------------------
-        stage('Prepare Test Hash') {
+        stage('Prepare Test Environment') {
             steps {
                 script {
                     // epoch seconds as a plain long